Merge branch 'development' into feature/website/new-logos

79 files changed, 5357 insertions, 242 deletions

diff --git a/.github/stale.yml b/.github/stale.yml
index af12c62d5..09eb40a77 100644
--- a/.github/stale.yml
+++ b/.github/stale.yml
@@ -1,7 +1,7 @@
 # Number of days of inactivity before an issue becomes stale
 daysUntilStale: 30
 # Number of days of inactivity before a stale issue is closed
-daysUntilClose: 7
+daysUntilClose: 30
 # Issues with these labels will never be considered stale
 exemptLabels:
     - pinned
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 1fea8f501..3e709b36f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -79,7 +79,20 @@ If using the Atom text editor, we recommend you install the following packages:
 *   VSCode: [prettier-vscode](https://marketplace.visualstudio.com/items?itemName=esbenp.prettier-vscode)
 *   Atom: [prettier-atom](https://atom.io/packages/prettier-atom)
 
-## Fix `submit-coverage` CI failure
+## Unenforced coding conventions
+
+A few of our coding conventions are not yet enforced by the linter/auto-formatter. Be careful to follow these conventions in your PR's.
+
+1.  Unused anonymous function parameters should be named with an underscore + number (e.g \_1, \_2, etc...)
+1.  There should be a new-line between methods in a class and between test cases.
+1.  If a string literal has the same value in two or more places, it should be a single constant referenced in both places.
+1.  Do not import from a project's `index.ts` (e.g import { Token } from '../src';). Always import from the source file itself.
+1.  Generic error variables should be named `err` instead of `e` or `error`.
+1.  If you _must_ cast a variable to any - try to type it back as fast as possible. (e.g., `const cw = ((zeroEx as any)._contractWrappers as ContractWrappers);`). This ensures subsequent code is type-safe.
+1.  Our enum conventions coincide with the recommended Typescript conventions, using capitalized keys, and all-caps snake-case values. Eg `GetStats = 'GET_STATS'`
+1.  All public, exported methods/functions/classes must have associated Javadoc-style comments.
+
+### Fix `submit-coverage` CI failure
 
 If you simply fork the repo and then create a PR from it, your PR will fail the `submit-coverage` check on CI. This is because the 0x CircleCI configuration sets the `COVERALLS_REPO_TOKEN` environment variable to the token for `0xProject/0x-monorepo`, but when running the check against your fork the token needs to match your repo's name `your-username/0x-monorepo`.
 
diff --git a/contracts/examples/package.json b/contracts/examples/package.json
index 77846241e..37b73f98c 100644
--- a/contracts/examples/package.json
+++ b/contracts/examples/package.json
@@ -13,7 +13,8 @@
         "build": "yarn pre_build && tsc -b",
         "build:ci": "yarn build",
         "pre_build": "run-s compile generate_contract_wrappers",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/contracts/extensions/CHANGELOG.json b/contracts/extensions/CHANGELOG.json
index 19ac770af..4f2b54988 100644
--- a/contracts/extensions/CHANGELOG.json
+++ b/contracts/extensions/CHANGELOG.json
@@ -1,5 +1,18 @@
 [
     {
+        "version": "1.1.0",
+        "changes": [
+            {
+                "note": "Added Balance Threshold Filter",
+                "pr": 1383
+            },
+            {
+                "note": "Add OrderMatcher",
+                "pr": 1117
+            }
+        ]
+    },
+    {
         "timestamp": 1544741676,
         "version": "1.0.2",
         "changes": [
diff --git a/contracts/extensions/compiler.json b/contracts/extensions/compiler.json
index 69d607b3e..1e21e6e6a 100644
--- a/contracts/extensions/compiler.json
+++ b/contracts/extensions/compiler.json
@@ -18,5 +18,5 @@
             }
         }
     },
-    "contracts": ["DutchAuction", "Forwarder"]
+    "contracts": ["BalanceThresholdFilter", "DutchAuction", "Forwarder", "OrderMatcher"]
 }
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/BalanceThresholdFilter.sol b/contracts/extensions/contracts/BalanceThresholdFilter/BalanceThresholdFilter.sol
new file mode 100644
index 000000000..16cacd461
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/BalanceThresholdFilter.sol
@@ -0,0 +1,45 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-interfaces/contracts/protocol/Exchange/IExchange.sol";
+import "./interfaces/IThresholdAsset.sol";
+import "./MixinBalanceThresholdFilterCore.sol";
+
+
+contract BalanceThresholdFilter is
+    MixinBalanceThresholdFilterCore
+{
+
+    /// @dev Constructs BalanceThresholdFilter.
+    /// @param exchange Address of 0x exchange.
+    /// @param thresholdAsset The asset that must be held by makers/takers.
+    /// @param balanceThreshold The minimum balance of `thresholdAsset` that must be held by makers/takers.
+    constructor(
+        address exchange,
+        address thresholdAsset,
+        uint256 balanceThreshold
+    )
+        public
+    {
+        EXCHANGE = IExchange(exchange);
+        THRESHOLD_ASSET = IThresholdAsset(thresholdAsset);
+        BALANCE_THRESHOLD = balanceThreshold;
+    }
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/MixinBalanceThresholdFilterCore.sol b/contracts/extensions/contracts/BalanceThresholdFilter/MixinBalanceThresholdFilterCore.sol
new file mode 100644
index 000000000..df830f36e
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/MixinBalanceThresholdFilterCore.sol
@@ -0,0 +1,135 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-libs/contracts/libs/LibExchangeSelectors.sol";
+import "@0x/contracts-libs/contracts/libs/LibOrder.sol";
+import "./mixins/MBalanceThresholdFilterCore.sol";
+import "./MixinExchangeCalldata.sol";
+
+
+contract MixinBalanceThresholdFilterCore is
+    MBalanceThresholdFilterCore,
+    MixinExchangeCalldata,
+    LibOrder,
+    LibExchangeSelectors
+{
+
+    /// @dev Executes an Exchange transaction iff the maker and taker meet 
+    ///      the hold at least `BALANCE_THRESHOLD` of the asset `THRESHOLD_ASSET` OR 
+    ///      the exchange function is a cancellation.
+    ///      Supported Exchange functions:
+    ///          batchFillOrders
+    ///          batchFillOrdersNoThrow
+    ///          batchFillOrKillOrders
+    ///          fillOrder
+    ///          fillOrderNoThrow
+    ///          fillOrKillOrder
+    ///          marketBuyOrders
+    ///          marketBuyOrdersNoThrow
+    ///          marketSellOrders
+    ///          marketSellOrdersNoThrow
+    ///          matchOrders
+    ///          cancelOrder
+    ///          batchCancelOrders
+    ///          cancelOrdersUpTo
+    ///     Trying to call any other exchange function will throw.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param signedExchangeTransaction AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes signedExchangeTransaction,
+        bytes signature
+    ) 
+        external
+    {
+        // Get accounts whose balances must be validated
+        address[] memory addressesToValidate = getAddressesToValidate(signerAddress);
+
+        // Validate account balances
+        uint256 balanceThreshold = BALANCE_THRESHOLD;
+        IThresholdAsset thresholdAsset = THRESHOLD_ASSET;
+        for (uint256 i = 0; i < addressesToValidate.length; ++i) {
+            uint256 addressBalance = thresholdAsset.balanceOf(addressesToValidate[i]);
+            require(
+                addressBalance >= balanceThreshold,
+                "AT_LEAST_ONE_ADDRESS_DOES_NOT_MEET_BALANCE_THRESHOLD"
+            );
+        }
+        emit ValidatedAddresses(addressesToValidate);
+        
+        // All addresses are valid. Execute exchange function.
+        EXCHANGE.executeTransaction(
+            salt,
+            signerAddress,
+            signedExchangeTransaction,
+            signature
+        );
+    }
+
+    /// @dev Constructs an array of addresses to be validated.
+    ///      Addresses depend on which Exchange function is to be called
+    ///      (defined by `signedExchangeTransaction` above).
+    /// @param signerAddress Address of transaction signer.
+    /// @return addressesToValidate Array of addresses to validate.
+    function getAddressesToValidate(address signerAddress)
+        internal pure
+        returns (address[] memory addressesToValidate)
+    {
+        bytes4 exchangeFunctionSelector = bytes4(exchangeCalldataload(0));
+        // solhint-disable expression-indent
+        if (
+            exchangeFunctionSelector == BATCH_FILL_ORDERS_SELECTOR              ||
+            exchangeFunctionSelector == BATCH_FILL_ORDERS_NO_THROW_SELECTOR     ||
+            exchangeFunctionSelector == BATCH_FILL_OR_KILL_ORDERS_SELECTOR      ||
+            exchangeFunctionSelector == MARKET_BUY_ORDERS_SELECTOR              ||
+            exchangeFunctionSelector == MARKET_BUY_ORDERS_NO_THROW_SELECTOR     ||
+            exchangeFunctionSelector == MARKET_SELL_ORDERS_SELECTOR             ||
+            exchangeFunctionSelector == MARKET_SELL_ORDERS_NO_THROW_SELECTOR
+        ) {
+            addressesToValidate = loadMakerAddressesFromOrderArray(0);
+            addressesToValidate = addressesToValidate.append(signerAddress);
+        } else if (
+            exchangeFunctionSelector == FILL_ORDER_SELECTOR             ||
+            exchangeFunctionSelector == FILL_ORDER_NO_THROW_SELECTOR    ||
+            exchangeFunctionSelector == FILL_OR_KILL_ORDER_SELECTOR
+        ) {
+            address makerAddress = loadMakerAddressFromOrder(0);
+            addressesToValidate = addressesToValidate.append(makerAddress);
+            addressesToValidate = addressesToValidate.append(signerAddress);
+        } else if (exchangeFunctionSelector == MATCH_ORDERS_SELECTOR) {
+            address leftMakerAddress = loadMakerAddressFromOrder(0);
+            addressesToValidate = addressesToValidate.append(leftMakerAddress);
+            address rightMakerAddress = loadMakerAddressFromOrder(1);
+            addressesToValidate = addressesToValidate.append(rightMakerAddress);
+            addressesToValidate = addressesToValidate.append(signerAddress);
+        } else if (
+            exchangeFunctionSelector != CANCEL_ORDER_SELECTOR           &&
+            exchangeFunctionSelector != BATCH_CANCEL_ORDERS_SELECTOR    &&
+            exchangeFunctionSelector != CANCEL_ORDERS_UP_TO_SELECTOR
+        ) {
+            revert("INVALID_OR_BLOCKED_EXCHANGE_SELECTOR");
+        }
+        // solhint-enable expression-indent
+        return addressesToValidate;
+    }
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/MixinExchangeCalldata.sol b/contracts/extensions/contracts/BalanceThresholdFilter/MixinExchangeCalldata.sol
new file mode 100644
index 000000000..bd26a468f
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/MixinExchangeCalldata.sol
@@ -0,0 +1,103 @@
+    
+    /*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "./mixins/MExchangeCalldata.sol";
+import "@0x/contracts-libs/contracts/libs/LibAddressArray.sol";
+
+
+contract MixinExchangeCalldata is 
+    MExchangeCalldata
+{
+
+    using LibAddressArray for address[];
+
+    /// @dev Emulates the `calldataload` opcode on the embedded Exchange calldata,
+    ///      which is accessed through `signedExchangeTransaction`.
+    /// @param offset  Offset into the Exchange calldata.
+    /// @return value  Corresponding 32 byte value stored at `offset`.
+    function exchangeCalldataload(uint256 offset)
+        internal pure
+        returns (bytes32 value)
+    {
+        assembly {
+            // Pointer to exchange transaction
+            // 0x04 for calldata selector
+            // 0x40 to access `signedExchangeTransaction`, which is the third parameter
+            let exchangeTxPtr := calldataload(0x44)
+
+            // Offset into Exchange calldata
+            // We compute this by adding 0x24 to the `exchangeTxPtr` computed above.
+            // 0x04 for calldata selector
+            // 0x20 for length field of `signedExchangeTransaction`
+            let exchangeCalldataOffset := add(exchangeTxPtr, add(0x24, offset))
+            value := calldataload(exchangeCalldataOffset)
+        }
+        return value;
+    }
+
+    /// @dev Convenience function that skips the 4 byte selector when loading
+    ///      from the embedded Exchange calldata.
+    /// @param offset  Offset into the Exchange calldata (minus the 4 byte selector)
+    /// @return value  Corresponding 32 byte value stored at `offset` + 4.
+    function loadExchangeData(uint256 offset)
+        internal pure
+        returns (bytes32 value)
+    {
+        value = exchangeCalldataload(offset + 4);
+        return value;
+    }
+
+    /// @dev Extracts the maker address from an order stored in the Exchange calldata
+    ///      (which is embedded in `signedExchangeTransaction`).
+    /// @param orderParamIndex  Index of the order in the Exchange function's signature.
+    /// @return makerAddress The extracted maker address.
+    function loadMakerAddressFromOrder(uint256 orderParamIndex)
+        internal pure
+        returns (address makerAddress)
+    {
+        uint256 orderOffsetInBytes = orderParamIndex * 32;
+        uint256 orderPtr = uint256(loadExchangeData(orderOffsetInBytes));
+        makerAddress = address(loadExchangeData(orderPtr));
+        return makerAddress;
+    }
+
+    /// @dev Extracts the maker addresses from an array of orders stored in the Exchange calldata
+    ///      (which is embedded in `signedExchangeTransaction`).
+    /// @param orderArrayParamIndex  Index of the order array in the Exchange function's signature
+    /// @return makerAddresses The extracted maker addresses.
+    function loadMakerAddressesFromOrderArray(uint256 orderArrayParamIndex)
+        internal pure
+        returns (address[] makerAddresses)
+    {
+        uint256 orderArrayOffsetInBytes = orderArrayParamIndex * 32;
+        uint256 orderArrayPtr = uint256(loadExchangeData(orderArrayOffsetInBytes));
+        uint256 orderArrayLength = uint256(loadExchangeData(orderArrayPtr));
+        uint256 orderArrayLengthInBytes = orderArrayLength * 32;
+        uint256 orderArrayElementPtr = orderArrayPtr + 32;
+        uint256 orderArrayElementEndPtr = orderArrayElementPtr + orderArrayLengthInBytes;
+        for (uint orderPtrOffset = orderArrayElementPtr; orderPtrOffset < orderArrayElementEndPtr; orderPtrOffset += 32) {
+            uint256 orderPtr = uint256(loadExchangeData(orderPtrOffset));
+            address makerAddress = address(loadExchangeData(orderPtr + orderArrayElementPtr));
+            makerAddresses = makerAddresses.append(makerAddress);
+        }
+        return makerAddresses;
+    }
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IBalanceThresholdFilterCore.sol b/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IBalanceThresholdFilterCore.sol
new file mode 100644
index 000000000..3d8e2bbd1
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IBalanceThresholdFilterCore.sol
@@ -0,0 +1,55 @@
+
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract IBalanceThresholdFilterCore {
+    
+    /// @dev Executes an Exchange transaction iff the maker and taker meet 
+    ///      the hold at least `BALANCE_THRESHOLD` of the asset `THRESHOLD_ASSET` OR 
+    ///      the exchange function is a cancellation.
+    ///      Supported Exchange functions:
+    ///         - batchFillOrders
+    ///         - batchFillOrdersNoThrow
+    ///         - batchFillOrKillOrders
+    ///         - fillOrder
+    ///         - fillOrderNoThrow
+    ///         - fillOrKillOrder
+    ///         - marketBuyOrders
+    ///         - marketBuyOrdersNoThrow
+    ///         - marketSellOrders
+    ///         - marketSellOrdersNoThrow
+    ///         - matchOrders
+    ///         - cancelOrder
+    ///         - batchCancelOrders
+    ///         - cancelOrdersUpTo
+    ///     Trying to call any other exchange function will throw.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param signedExchangeTransaction AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes signedExchangeTransaction,
+        bytes signature
+    ) 
+        external;
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IThresholdAsset.sol b/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IThresholdAsset.sol
new file mode 100644
index 000000000..3e424b9f4
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/interfaces/IThresholdAsset.sol
@@ -0,0 +1,31 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract IThresholdAsset {
+
+    /// @param _owner The address from which the balance will be retrieved
+    /// @return Balance of owner
+    function balanceOf(address _owner)
+        external
+        view
+        returns (uint256);
+
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MBalanceThresholdFilterCore.sol b/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MBalanceThresholdFilterCore.sol
new file mode 100644
index 000000000..b8b67e6ee
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MBalanceThresholdFilterCore.sol
@@ -0,0 +1,54 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-interfaces/contracts/protocol/Exchange/IExchange.sol";
+import "../interfaces/IThresholdAsset.sol";
+import "../interfaces/IBalanceThresholdFilterCore.sol";
+
+
+contract MBalanceThresholdFilterCore is
+    IBalanceThresholdFilterCore
+{
+
+    // Points to 0x exchange contract
+    // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+
+    // The asset that must be held by makers/takers
+    IThresholdAsset internal THRESHOLD_ASSET;
+
+    // The minimum balance of `THRESHOLD_ASSET` that must be held by makers/takers
+    uint256 internal BALANCE_THRESHOLD;
+    // solhint-enable var-name-mixedcase
+
+    // Addresses that hold at least `BALANCE_THRESHOLD` of `THRESHOLD_ASSET`
+    event ValidatedAddresses (
+        address[] addresses
+    );
+
+    /// @dev Constructs an array of addresses to be validated.
+    ///      Addresses depend on which Exchange function is to be called
+    ///      (defined by `signedExchangeTransaction` above).
+    /// @param signerAddress Address of transaction signer.
+    /// @return addressesToValidate Array of addresses to validate.
+    function getAddressesToValidate(address signerAddress)
+        internal pure
+        returns (address[] memory addressesToValidate);
+}
diff --git a/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MExchangeCalldata.sol b/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MExchangeCalldata.sol
new file mode 100644
index 000000000..bf2940fe1
--- /dev/null
+++ b/contracts/extensions/contracts/BalanceThresholdFilter/mixins/MExchangeCalldata.sol
@@ -0,0 +1,56 @@
+    
+    /*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract MExchangeCalldata {
+
+    /// @dev Emulates the `calldataload` opcode on the embedded Exchange calldata,
+    ///      which is accessed through `signedExchangeTransaction`.
+    /// @param offset  Offset into the Exchange calldata.
+    /// @return value  Corresponding 32 byte value stored at `offset`.
+    function exchangeCalldataload(uint256 offset)
+        internal pure
+        returns (bytes32 value);
+
+    /// @dev Convenience function that skips the 4 byte selector when loading
+    ///      from the embedded Exchange calldata.
+    /// @param offset  Offset into the Exchange calldata (minus the 4 byte selector)
+    /// @return value  Corresponding 32 byte value stored at `offset` + 4.
+    function loadExchangeData(uint256 offset)
+        internal pure
+        returns (bytes32 value);
+
+    /// @dev Extracts the maker address from an order stored in the Exchange calldata
+    ///      (which is embedded in `signedExchangeTransaction`).
+    /// @param orderParamIndex  Index of the order in the Exchange function's signature.
+    /// @return makerAddress The extracted maker address.
+    function loadMakerAddressFromOrder(uint256 orderParamIndex)
+        internal pure
+        returns (address makerAddress);
+
+    /// @dev Extracts the maker addresses from an array of orders stored in the Exchange calldata
+    ///      (which is embedded in `signedExchangeTransaction`).
+    /// @param orderArrayParamIndex  Index of the order array in the Exchange function's signature
+    /// @return makerAddresses The extracted maker addresses.
+    function loadMakerAddressesFromOrderArray(uint256 orderArrayParamIndex)
+        internal pure
+        returns (address[] makerAddresses);
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/MixinAssets.sol b/contracts/extensions/contracts/OrderMatcher/MixinAssets.sol
new file mode 100644
index 000000000..323998705
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/MixinAssets.sol
@@ -0,0 +1,195 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-utils/contracts/utils/LibBytes/LibBytes.sol";
+import "@0x/contracts-utils/contracts/utils/Ownable/Ownable.sol";
+import "@0x/contracts-tokens/contracts/tokens/ERC20Token/IERC20Token.sol";
+import "@0x/contracts-tokens/contracts/tokens/ERC721Token/IERC721Token.sol";
+import "./mixins/MAssets.sol";
+import "./libs/LibConstants.sol";
+
+
+contract MixinAssets is
+    MAssets,
+    Ownable,
+    LibConstants
+{
+    using LibBytes for bytes;
+
+    /// @dev Withdraws assets from this contract. The contract requires a ZRX balance in order to 
+    ///      function optimally, and this function allows the ZRX to be withdrawn by owner. It may also be
+    ///      used to withdraw assets that were accidentally sent to this contract.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to withdraw.
+    function withdrawAsset(
+        bytes assetData,
+        uint256 amount
+    )
+        external
+        onlyOwner
+    {
+        transferAssetToSender(assetData, amount);
+    }
+
+    /// @dev Approves or disapproves an AssetProxy to spend asset.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveAssetProxy(
+        bytes assetData,
+        uint256 amount
+    )
+        external
+        onlyOwner
+    {
+        bytes4 proxyId = assetData.readBytes4(0);
+
+        if (proxyId == ERC20_DATA_ID) {
+            approveERC20Token(assetData, amount);
+        } else if (proxyId == ERC721_DATA_ID) {
+            approveERC721Token(assetData, amount);
+        } else {
+            revert("UNSUPPORTED_ASSET_PROXY");
+        }
+    }
+
+    /// @dev Transfers given amount of asset to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferAssetToSender(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        bytes4 proxyId = assetData.readBytes4(0);
+
+        if (proxyId == ERC20_DATA_ID) {
+            transferERC20Token(assetData, amount);
+        } else if (proxyId == ERC721_DATA_ID) {
+            transferERC721Token(assetData, amount);
+        } else {
+            revert("UNSUPPORTED_ASSET_PROXY");
+        }
+    }
+
+    /// @dev Decodes ERC20 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        // 4 byte id + 12 0 bytes before ABI encoded token address.
+        address token = assetData.readAddress(16);
+
+        // Transfer tokens.
+        // We do a raw call so we can check the success separate
+        // from the return data.
+        bool success = token.call(abi.encodeWithSelector(
+            ERC20_TRANSFER_SELECTOR,
+            msg.sender,
+            amount
+        ));
+        require(
+            success,
+            "TRANSFER_FAILED"
+        );
+        
+        // Check return data.
+        // If there is no return data, we assume the token incorrectly
+        // does not return a bool. In this case we expect it to revert
+        // on failure, which was handled above.
+        // If the token does return data, we require that it is a single
+        // value that evaluates to true.
+        assembly {
+            if returndatasize {
+                success := 0
+                if eq(returndatasize, 32) {
+                    // First 64 bytes of memory are reserved scratch space
+                    returndatacopy(0, 0, 32)
+                    success := mload(0)
+                }
+            }
+        }
+        require(
+            success,
+            "TRANSFER_FAILED"
+        );
+    }
+
+    /// @dev Decodes ERC721 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        require(
+            amount == 1,
+            "INVALID_AMOUNT"
+        );
+        // Decode asset data.
+        // 4 byte id + 12 0 bytes before ABI encoded token address.
+        address token = assetData.readAddress(16);
+        // 4 byte id + 32 byte ABI encoded token address before token id.
+        uint256 tokenId = assetData.readUint256(36);
+
+        // Perform transfer.
+        IERC721Token(token).transferFrom(
+            address(this),
+            msg.sender,
+            tokenId
+        );
+    }
+
+    /// @dev Sets approval for ERC20 AssetProxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        address token = assetData.readAddress(16);
+        require(
+            IERC20Token(token).approve(ERC20_PROXY_ADDRESS, amount),
+            "APPROVAL_FAILED"
+        );
+    }
+
+    /// @dev Sets approval for ERC721 AssetProxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        address token = assetData.readAddress(16);
+        bool approval = amount >= 1;
+        IERC721Token(token).setApprovalForAll(ERC721_PROXY_ADDRESS, approval);
+    }
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/MixinMatchOrders.sol b/contracts/extensions/contracts/OrderMatcher/MixinMatchOrders.sol
new file mode 100644
index 000000000..f75cecdc1
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/MixinMatchOrders.sol
@@ -0,0 +1,86 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "@0x/contracts-libs/contracts/libs/LibOrder.sol";
+import "@0x/contracts-libs/contracts/libs/LibFillResults.sol";
+import "@0x/contracts-utils/contracts/utils/Ownable/Ownable.sol";
+
+
+contract MixinMatchOrders is
+    Ownable,
+    LibConstants
+{
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order is then used to fill the right order as much as possible.
+    ///      This results in a spread being taken in terms of both assets. The spread is held within this contract.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public
+        onlyOwner
+    {
+        // Match orders, maximally filling `leftOrder`
+        LibFillResults.MatchedFillResults memory matchedFillResults = EXCHANGE.matchOrders(
+            leftOrder,
+            rightOrder,
+            leftSignature,
+            rightSignature
+        );
+
+        uint256 leftMakerAssetSpreadAmount = matchedFillResults.leftMakerAssetSpreadAmount;
+        uint256 rightOrderTakerAssetAmount = rightOrder.takerAssetAmount;
+
+        // Do not attempt to call `fillOrder` if no spread was taken or `rightOrder` has been completely filled
+        if (leftMakerAssetSpreadAmount == 0 || matchedFillResults.right.takerAssetFilledAmount == rightOrderTakerAssetAmount) {
+            return;
+        }
+
+        // The `assetData` fields of the `rightOrder` could have been null for the `matchOrders` call. We reassign them before calling `fillOrder`.
+        rightOrder.makerAssetData = leftOrder.takerAssetData;
+        rightOrder.takerAssetData = leftOrder.makerAssetData;
+
+        // Query `rightOrder` info to check if it has been completely filled
+        // We need to make this check in case the `rightOrder` was partially filled before the `matchOrders` call
+        LibOrder.OrderInfo memory orderInfo = EXCHANGE.getOrderInfo(rightOrder);
+
+        // Do not attempt to call `fillOrder` if order has been completely filled
+        if (orderInfo.orderTakerAssetFilledAmount == rightOrderTakerAssetAmount) {
+            return;
+        }
+
+        // We do not need to pass in a signature since it was already validated in the `matchOrders` call
+        EXCHANGE.fillOrder(
+            rightOrder,
+            leftMakerAssetSpreadAmount,
+            ""
+        );
+    }
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/OrderMatcher.sol b/contracts/extensions/contracts/OrderMatcher/OrderMatcher.sol
new file mode 100644
index 000000000..4879b7bca
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/OrderMatcher.sol
@@ -0,0 +1,38 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "@0x/contracts-utils/contracts/utils/Ownable/Ownable.sol";
+import "./libs/LibConstants.sol";
+import "./MixinMatchOrders.sol";
+import "./MixinAssets.sol";
+
+
+// solhint-disable no-empty-blocks
+contract OrderMatcher is
+    MixinMatchOrders,
+    MixinAssets
+{
+    constructor (address _exchange)
+        public
+        LibConstants(_exchange)
+        Ownable()
+    {}
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/interfaces/IAssets.sol b/contracts/extensions/contracts/OrderMatcher/interfaces/IAssets.sol
new file mode 100644
index 000000000..a0b3aa4c7
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/interfaces/IAssets.sol
@@ -0,0 +1,43 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract IAssets {
+
+    /// @dev Withdraws assets from this contract. The contract requires a ZRX balance in order to 
+    ///      function optimally, and this function allows the ZRX to be withdrawn by owner. It may also be
+    ///      used to withdraw assets that were accidentally sent to this contract.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to withdraw.
+    function withdrawAsset(
+        bytes assetData,
+        uint256 amount
+    )
+        external;
+
+    /// @dev Approves or disapproves an AssetProxy to spend asset.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveAssetProxy(
+        bytes assetData,
+        uint256 amount
+    )
+        external;
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/interfaces/IMatchOrders.sol b/contracts/extensions/contracts/OrderMatcher/interfaces/IMatchOrders.sol
new file mode 100644
index 000000000..19bcbb326
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/interfaces/IMatchOrders.sol
@@ -0,0 +1,43 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "@0x/contracts-libs/contracts/libs/LibOrder.sol";
+
+
+contract IMatchOrders {
+
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order is then used to fill the right order as much as possible.
+    ///      This results in a spread being taken in terms of both assets. The spread is held within this contract.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public;
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/interfaces/IOrderMatcher.sol b/contracts/extensions/contracts/OrderMatcher/interfaces/IOrderMatcher.sol
new file mode 100644
index 000000000..9b6ea26d8
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/interfaces/IOrderMatcher.sol
@@ -0,0 +1,31 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contract-utils/contracts/utils/Ownable/IOwnable.sol";
+import "./IMatchOrders.sol";
+import "./IAssets.sol";
+
+
+// solhint-disable no-empty-blocks
+contract IOrderMatcher is
+    IOwnable,
+    IMatchOrders,
+    IAssets
+{}
diff --git a/contracts/extensions/contracts/OrderMatcher/libs/LibConstants.sol b/contracts/extensions/contracts/OrderMatcher/libs/LibConstants.sol
new file mode 100644
index 000000000..bd6a5e0ee
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/libs/LibConstants.sol
@@ -0,0 +1,56 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-interfaces/contracts/protocol/Exchange/IExchange.sol";
+
+
+contract LibConstants {
+
+    // bytes4(keccak256("transfer(address,uint256)"))
+    bytes4 constant internal ERC20_TRANSFER_SELECTOR = 0xa9059cbb;
+    // bytes4(keccak256("ERC20Token(address)"))
+    bytes4 constant internal ERC20_DATA_ID = 0xf47261b0;
+    // bytes4(keccak256("ERC721Token(address,uint256)"))
+    bytes4 constant internal ERC721_DATA_ID = 0x02571792;
+ 
+     // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+    address internal ERC20_PROXY_ADDRESS;
+    address internal ERC721_PROXY_ADDRESS;
+    // solhint-enable var-name-mixedcase
+
+    constructor (address _exchange)
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+
+        ERC20_PROXY_ADDRESS = EXCHANGE.getAssetProxy(ERC20_DATA_ID);
+        require(
+            ERC20_PROXY_ADDRESS != address(0),
+            "UNREGISTERED_ASSET_PROXY"
+        );
+
+        ERC721_PROXY_ADDRESS = EXCHANGE.getAssetProxy(ERC721_DATA_ID);
+        require(
+            ERC721_PROXY_ADDRESS != address(0),
+            "UNREGISTERED_ASSET_PROXY"
+        );
+    }
+}
diff --git a/contracts/extensions/contracts/OrderMatcher/mixins/MAssets.sol b/contracts/extensions/contracts/OrderMatcher/mixins/MAssets.sol
new file mode 100644
index 000000000..32cfddf1c
--- /dev/null
+++ b/contracts/extensions/contracts/OrderMatcher/mixins/MAssets.sol
@@ -0,0 +1,71 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "../interfaces/IAssets.sol";
+
+
+contract MAssets is
+    IAssets
+{
+    /// @dev Transfers given amount of asset to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferAssetToSender(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Decodes ERC20 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Decodes ERC721 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Sets approval for ERC20 AssetProxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Sets approval for ERC721 AssetProxy.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to approve for respective proxy.
+    function approveERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+}
diff --git a/contracts/extensions/package.json b/contracts/extensions/package.json
index 938e1138c..d0caa030e 100644
--- a/contracts/extensions/package.json
+++ b/contracts/extensions/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
@@ -31,7 +32,7 @@
         "lint-contracts": "solhint -c ../.solhint.json contracts/**/**/**/**/*.sol"
     },
     "config": {
-        "abis": "generated-artifacts/@(DutchAuction|Forwarder).json"
+        "abis": "generated-artifacts/@(BalanceThresholdFilter|DutchAuction|Forwarder|OrderMatcher).json"
     },
     "repository": {
         "type": "git",
diff --git a/contracts/extensions/src/artifacts/index.ts b/contracts/extensions/src/artifacts/index.ts
index 7588178f0..a8bd34b4e 100644
--- a/contracts/extensions/src/artifacts/index.ts
+++ b/contracts/extensions/src/artifacts/index.ts
@@ -1,9 +1,13 @@
 import { ContractArtifact } from 'ethereum-types';
 
+import * as BalanceThresholdFilter from '../../generated-artifacts/BalanceThresholdFilter.json';
 import * as DutchAuction from '../../generated-artifacts/DutchAuction.json';
 import * as Forwarder from '../../generated-artifacts/Forwarder.json';
+import * as OrderMatcher from '../../generated-artifacts/OrderMatcher.json';
 
 export const artifacts = {
+    BalanceThresholdFilter: BalanceThresholdFilter as ContractArtifact,
     DutchAuction: DutchAuction as ContractArtifact,
     Forwarder: Forwarder as ContractArtifact,
+    OrderMatcher: OrderMatcher as ContractArtifact,
 };
diff --git a/contracts/extensions/src/wrappers/index.ts b/contracts/extensions/src/wrappers/index.ts
index 90880e37f..4d075ee13 100644
--- a/contracts/extensions/src/wrappers/index.ts
+++ b/contracts/extensions/src/wrappers/index.ts
@@ -1,2 +1,4 @@
+export * from '../../generated-wrappers/balance_threshold_filter';
 export * from '../../generated-wrappers/dutch_auction';
 export * from '../../generated-wrappers/forwarder';
+export * from '../../generated-wrappers/order_matcher';
diff --git a/contracts/extensions/test/extensions/balance_threshold_filter.ts b/contracts/extensions/test/extensions/balance_threshold_filter.ts
new file mode 100644
index 000000000..07199d60b
--- /dev/null
+++ b/contracts/extensions/test/extensions/balance_threshold_filter.ts
@@ -0,0 +1,1644 @@
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import { assetDataUtils } from '@0x/order-utils';
+import { Order, RevertReason, SignedOrder } from '@0x/types';
+import { BigNumber } from '@0x/utils';
+import { Web3Wrapper } from '@0x/web3-wrapper';
+import * as chai from 'chai';
+import { TransactionReceiptWithDecodedLogs } from 'ethereum-types';
+import * as _ from 'lodash';
+
+import {
+    artifacts as protocolArtifacts,
+    ERC20Wrapper,
+    ERC721Wrapper,
+    ExchangeContract,
+    ExchangeWrapper,
+} from '@0x/contracts-protocol';
+import {
+    chaiSetup,
+    constants,
+    ContractName,
+    ERC20BalancesByOwner,
+    expectTransactionFailedAsync,
+    OrderFactory,
+    OrderStatus,
+    provider,
+    TransactionFactory,
+    txDefaults,
+    web3Wrapper,
+} from '@0x/contracts-test-utils';
+import { DummyERC20TokenContract } from '@0x/contracts-tokens';
+
+import { BalanceThresholdFilterContract } from '../../generated-wrappers/balance_threshold_filter';
+import { artifacts } from '../../src/artifacts';
+import { BalanceThresholdWrapper } from '../utils/balance_threshold_wrapper';
+
+chaiSetup.configure();
+const expect = chai.expect;
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+const DECIMALS_DEFAULT = 18;
+
+interface ValidatedAddressesLog {
+    args: { addresses: string[] };
+}
+
+describe(ContractName.BalanceThresholdFilter, () => {
+    const takerAssetAmount = Web3Wrapper.toBaseUnitAmount(new BigNumber(500), DECIMALS_DEFAULT);
+    const makerAssetAmount = Web3Wrapper.toBaseUnitAmount(new BigNumber(1000), DECIMALS_DEFAULT);
+    const takerAssetFillAmount = Web3Wrapper.toBaseUnitAmount(new BigNumber(250), DECIMALS_DEFAULT);
+
+    let validMakerAddress: string;
+    let validMakerAddress2: string;
+    let owner: string;
+    let validTakerAddress: string;
+    let feeRecipientAddress: string;
+    let invalidAddress: string;
+    let defaultMakerAssetAddress: string;
+    let defaultTakerAssetAddress: string;
+    let zrxAssetData: string;
+    let zrxToken: DummyERC20TokenContract;
+    let exchangeInstance: ExchangeContract;
+    let exchangeWrapper: ExchangeWrapper;
+
+    let orderFactory: OrderFactory;
+    let orderFactory2: OrderFactory;
+    let invalidOrderFactory: OrderFactory;
+    let erc20Wrapper: ERC20Wrapper;
+    let erc20Balances: ERC20BalancesByOwner;
+    let erc20TakerBalanceThresholdWrapper: BalanceThresholdWrapper;
+    let erc721TakerBalanceThresholdWrapper: BalanceThresholdWrapper;
+    let erc721MakerBalanceThresholdWrapper: BalanceThresholdWrapper;
+    let erc721NonValidBalanceThresholdWrapper: BalanceThresholdWrapper;
+
+    let defaultOrderParams: Partial<Order>;
+    let validSignedOrder: SignedOrder;
+    let validSignedOrder2: SignedOrder;
+
+    let erc721BalanceThresholdFilterInstance: BalanceThresholdFilterContract;
+    let erc20BalanceThresholdFilterInstance: BalanceThresholdFilterContract;
+
+    const assertValidatedAddressesLog = async (
+        txReceipt: TransactionReceiptWithDecodedLogs,
+        expectedValidatedAddresses: string[],
+    ) => {
+        expect(txReceipt.logs.length).to.be.gte(1);
+        const validatedAddressesLog = (txReceipt.logs[0] as any) as ValidatedAddressesLog;
+        const validatedAddresses = validatedAddressesLog.args.addresses;
+        // @HACK-hysz: Nested addresses are not translated to lower-case but this will change once
+        //             the new ABI Encoder/Decoder is used by the contract templates.
+        const validatedAddressesNormalized: string[] = [];
+        _.each(validatedAddresses, address => {
+            const normalizedAddress = _.toLower(address);
+            validatedAddressesNormalized.push(normalizedAddress);
+        });
+        expect(validatedAddressesNormalized).to.be.deep.equal(expectedValidatedAddresses);
+    };
+
+    before(async () => {
+        // Create accounts
+        await blockchainLifecycle.startAsync();
+        const accounts = await web3Wrapper.getAvailableAddressesAsync();
+        const usedAddresses = ([
+            owner,
+            validMakerAddress,
+            validMakerAddress2,
+            validTakerAddress,
+            feeRecipientAddress,
+            invalidAddress,
+        ] = accounts);
+        const takerPrivateKey = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(validTakerAddress)];
+        const makerPrivateKey = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(validMakerAddress)];
+        const secondMakerPrivateKey = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(validMakerAddress2)];
+        const invalidAddressPrivateKey = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(invalidAddress)];
+        // Create wrappers
+        erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
+        const validAddresses = _.cloneDeepWith(usedAddresses);
+        _.remove(validAddresses, (address: string) => {
+            return address === invalidAddress;
+        });
+        const erc721Wrapper = new ERC721Wrapper(provider, validAddresses, owner);
+        // Deploy ERC20 tokens
+        const numDummyErc20ToDeploy = 4;
+        let erc20TokenA: DummyERC20TokenContract;
+        let erc20TokenB: DummyERC20TokenContract;
+        let erc20BalanceThresholdAsset: DummyERC20TokenContract;
+        [erc20TokenA, erc20TokenB, zrxToken, erc20BalanceThresholdAsset] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
+        defaultMakerAssetAddress = erc20TokenA.address;
+        defaultTakerAssetAddress = erc20TokenB.address;
+        zrxAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
+        // Create proxies
+        const erc20Proxy = await erc20Wrapper.deployProxyAsync();
+        await erc20Wrapper.setBalancesAndAllowancesAsync();
+        // Deploy Exchange contract
+        exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
+            protocolArtifacts.Exchange,
+            provider,
+            txDefaults,
+            zrxAssetData,
+        );
+        exchangeWrapper = new ExchangeWrapper(exchangeInstance, provider);
+        // Register proxies
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
+        await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchangeInstance.address, {
+            from: owner,
+        });
+        // Deploy Balance Threshold Filters
+        // One uses an ERC721 token as its balance threshold asset; the other uses an ERC20
+        const erc721alanceThreshold = new BigNumber(1);
+        await erc721Wrapper.deployProxyAsync();
+        const [erc721BalanceThresholdAsset] = await erc721Wrapper.deployDummyTokensAsync();
+        await erc721Wrapper.setBalancesAndAllowancesAsync();
+        erc721BalanceThresholdFilterInstance = await BalanceThresholdFilterContract.deployFrom0xArtifactAsync(
+            artifacts.BalanceThresholdFilter,
+            provider,
+            txDefaults,
+            exchangeInstance.address,
+            erc721BalanceThresholdAsset.address,
+            erc721alanceThreshold,
+        );
+        const erc20BalanceThreshold = Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 10);
+        erc20BalanceThresholdFilterInstance = await BalanceThresholdFilterContract.deployFrom0xArtifactAsync(
+            artifacts.BalanceThresholdFilter,
+            provider,
+            txDefaults,
+            exchangeInstance.address,
+            erc20BalanceThresholdAsset.address,
+            erc20BalanceThreshold,
+        );
+        // Default order parameters
+        defaultOrderParams = {
+            exchangeAddress: exchangeInstance.address,
+            feeRecipientAddress,
+            makerAssetData: assetDataUtils.encodeERC20AssetData(defaultMakerAssetAddress),
+            takerAssetData: assetDataUtils.encodeERC20AssetData(defaultTakerAssetAddress),
+            makerAssetAmount,
+            takerAssetAmount,
+            makerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), DECIMALS_DEFAULT),
+            takerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(150), DECIMALS_DEFAULT),
+            senderAddress: erc721BalanceThresholdFilterInstance.address,
+        };
+        // Create two order factories with valid makers (who meet the threshold balance), and
+        // one factory for an invalid address (that does not meet the threshold balance)
+        // Valid order factory #1
+        const defaultOrderParams1 = {
+            makerAddress: validMakerAddress,
+            ...defaultOrderParams,
+        };
+        orderFactory = new OrderFactory(makerPrivateKey, defaultOrderParams1);
+        // Valid order factory #2
+        const defaultOrderParams2 = {
+            makerAddress: validMakerAddress2,
+            ...defaultOrderParams,
+        };
+        orderFactory2 = new OrderFactory(secondMakerPrivateKey, defaultOrderParams2);
+        // Invalid order factory
+        const defaultNonValidOrderParams = {
+            makerAddress: invalidAddress,
+            ...defaultOrderParams,
+        };
+        invalidOrderFactory = new OrderFactory(invalidAddressPrivateKey, defaultNonValidOrderParams);
+        // Create Balance Thresold Wrappers
+        erc20TakerBalanceThresholdWrapper = new BalanceThresholdWrapper(
+            erc20BalanceThresholdFilterInstance,
+            exchangeInstance,
+            new TransactionFactory(takerPrivateKey, exchangeInstance.address),
+            provider,
+        );
+        erc721TakerBalanceThresholdWrapper = new BalanceThresholdWrapper(
+            erc721BalanceThresholdFilterInstance,
+            exchangeInstance,
+            new TransactionFactory(takerPrivateKey, exchangeInstance.address),
+            provider,
+        );
+        erc721MakerBalanceThresholdWrapper = new BalanceThresholdWrapper(
+            erc721BalanceThresholdFilterInstance,
+            exchangeInstance,
+            new TransactionFactory(makerPrivateKey, exchangeInstance.address),
+            provider,
+        );
+        erc721NonValidBalanceThresholdWrapper = new BalanceThresholdWrapper(
+            erc721BalanceThresholdFilterInstance,
+            exchangeInstance,
+            new TransactionFactory(invalidAddressPrivateKey, exchangeInstance.address),
+            provider,
+        );
+    });
+    beforeEach(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    afterEach(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+
+    describe('General Sanity Checks', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both maker/taker when both maker and taker exceed the balance threshold of an ERC20 token', async () => {
+            const validSignedOrderERC20Sender = await orderFactory.newSignedOrderAsync({
+                ...defaultOrderParams,
+                makerAddress: validMakerAddress,
+                senderAddress: erc20TakerBalanceThresholdWrapper.getBalanceThresholdAddress(),
+            });
+            // Execute a valid fill
+            const txReceipt = await erc20TakerBalanceThresholdWrapper.fillOrderAsync(
+                validSignedOrderERC20Sender,
+                validTakerAddress,
+                { takerAssetFillAmount },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [validSignedOrder.makerAddress, validTakerAddress];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
+            );
+        });
+        it('should revert if the Exchange transaction function is not supported', async () => {
+            // Create signed order without the fillOrder function selector
+            const salt = new BigNumber(0);
+            const badSelectorHex = '0x00000000';
+            const signatureHex = '0x';
+            // Call valid forwarder
+            return expectTransactionFailedAsync(
+                erc721BalanceThresholdFilterInstance.executeTransaction.sendTransactionAsync(
+                    salt,
+                    validTakerAddress,
+                    badSelectorHex,
+                    signatureHex,
+                ),
+                RevertReason.InvalidOrBlockedExchangeSelector,
+            );
+        });
+        it('should revert if senderAddress is not set to the valid forwarding contract', async () => {
+            // Create signed order with incorrect senderAddress
+            const notBalanceThresholdFilterAddress = zrxToken.address;
+            const signedOrderWithBadSenderAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: notBalanceThresholdFilterAddress,
+            });
+            // Call valid forwarder
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.fillOrderAsync(signedOrderWithBadSenderAddress, validTakerAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.FailedExecution,
+            );
+        });
+    });
+
+    describe('batchFillOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both maker and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.batchFillOrdersAsync(orders, validTakerAddress, {
+                takerAssetFillAmounts,
+            });
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const cumulativeTakerAssetFillAmount = takerAssetFillAmount.times(2);
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount)
+                .times(2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount.times(2)),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.times(2).add(takerFeePaid)),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.batchFillOrdersAsync(orders, validTakerAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.batchFillOrdersAsync(orders, invalidAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('batchFillOrdersNoThrow', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both maker and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.batchFillOrdersNoThrowAsync(
+                orders,
+                validTakerAddress,
+                {
+                    takerAssetFillAmounts,
+                    // HACK(albrow): We need to hardcode the gas estimate here because
+                    // the Geth gas estimator doesn't work with the way we use
+                    // delegatecall and swallow errors.
+                    gas: 600000,
+                },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const cumulativeTakerAssetFillAmount = takerAssetFillAmount.times(2);
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount)
+                .times(2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount.times(2)),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.times(2).add(takerFeePaid)),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.batchFillOrdersNoThrowAsync(orders, validTakerAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.batchFillOrdersNoThrowAsync(orders, invalidAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('batchFillOrKillOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both makers and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.batchFillOrKillOrdersAsync(
+                orders,
+                validTakerAddress,
+                { takerAssetFillAmounts },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const cumulativeTakerAssetFillAmount = takerAssetFillAmount.times(2);
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount)
+                .times(2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount.times(2)),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.times(2).add(takerFeePaid)),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.batchFillOrKillOrdersAsync(orders, validTakerAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, takerAssetFillAmount];
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.batchFillOrKillOrdersAsync(orders, invalidAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if one takerAssetFillAmount is not fully filled', async () => {
+            const tooBigTakerAssetFillAmount = validSignedOrder.takerAssetAmount.times(2);
+            const orders = [validSignedOrder, validSignedOrder2];
+            const takerAssetFillAmounts = [takerAssetFillAmount, tooBigTakerAssetFillAmount];
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.batchFillOrKillOrdersAsync(orders, validTakerAddress, {
+                    takerAssetFillAmounts,
+                }),
+                RevertReason.FailedExecution,
+            );
+        });
+    });
+
+    describe('fillOrder', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both maker/taker when both maker and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.fillOrderAsync(
+                validSignedOrder,
+                validTakerAddress,
+                { takerAssetFillAmount },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [validSignedOrder.makerAddress, validTakerAddress];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
+            );
+        });
+        it('should revert if maker does not meet the balance threshold', async () => {
+            // Create signed order with non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: erc721BalanceThresholdFilterInstance.address,
+                makerAddress: invalidAddress,
+            });
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.fillOrderAsync(signedOrderWithBadMakerAddress, validTakerAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.fillOrderAsync(validSignedOrder, invalidAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('fillOrderNoThrow', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both maker/taker when both maker and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.fillOrderNoThrowAsync(
+                validSignedOrder,
+                validTakerAddress,
+                {
+                    takerAssetFillAmount,
+                    // HACK(albrow): We need to hardcode the gas estimate here because
+                    // the Geth gas estimator doesn't work with the way we use
+                    // delegatecall and swallow errors.
+                    gas: 600000,
+                },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [validSignedOrder.makerAddress, validTakerAddress];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
+            );
+        });
+        it('should revert if maker does not meet the balance threshold', async () => {
+            // Create signed order with non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: erc721BalanceThresholdFilterInstance.address,
+                makerAddress: invalidAddress,
+            });
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.fillOrderNoThrowAsync(
+                    signedOrderWithBadMakerAddress,
+                    validTakerAddress,
+                    { takerAssetFillAmount },
+                ),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.fillOrderNoThrowAsync(validSignedOrder, invalidAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('fillOrKillOrder', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both maker/taker when both maker and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const takerAssetFillAmount_ = validSignedOrder.takerAssetAmount;
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.fillOrKillOrderAsync(
+                validSignedOrder,
+                validTakerAddress,
+                { takerAssetFillAmount: takerAssetFillAmount_ },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [validSignedOrder.makerAddress, validTakerAddress];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount = takerAssetFillAmount_
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid = validSignedOrder.makerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee
+                .times(makerAssetFillAmount)
+                .dividedToIntegerBy(validSignedOrder.makerAssetAmount);
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(makerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount_),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(makerFeePaid),
+            );
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount_),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(makerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
+            );
+        });
+        it('should revert if maker does not meet the balance threshold', async () => {
+            // Create signed order with non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: erc721BalanceThresholdFilterInstance.address,
+                makerAddress: invalidAddress,
+            });
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.fillOrKillOrderAsync(
+                    signedOrderWithBadMakerAddress,
+                    validTakerAddress,
+                    { takerAssetFillAmount },
+                ),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.fillOrKillOrderAsync(validSignedOrder, invalidAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if takerAssetFillAmount is not fully filled', async () => {
+            const tooBigTakerAssetFillAmount = validSignedOrder.takerAssetAmount.times(2);
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.fillOrKillOrderAsync(validSignedOrder, validTakerAddress, {
+                    takerAssetFillAmount: tooBigTakerAssetFillAmount,
+                }),
+                RevertReason.FailedExecution,
+            );
+        });
+    });
+
+    describe('marketSellOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both makers and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const cumulativeTakerAssetFillAmount = validSignedOrder.takerAssetAmount.plus(takerAssetFillAmount);
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.marketSellOrdersAsync(
+                orders,
+                validTakerAddress,
+                { takerAssetFillAmount: cumulativeTakerAssetFillAmount },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount2 = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid2 = validSignedOrder2.makerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid2 = validSignedOrder2.takerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee.plus(takerFeePaid2);
+            const cumulativeMakerAssetFillAmount = validSignedOrder.makerAssetAmount.plus(makerAssetFillAmount2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(validSignedOrder.makerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(validSignedOrder.takerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(validSignedOrder.makerFee),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount2),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid2),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(cumulativeMakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address]
+                    .add(validSignedOrder.makerFee)
+                    .add(makerFeePaid2)
+                    .add(takerFeePaid),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.marketSellOrdersAsync(orders, validTakerAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.marketSellOrdersAsync(orders, invalidAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('marketSellOrdersNoThrow', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both makers and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const cumulativeTakerAssetFillAmount = validSignedOrder.takerAssetAmount.plus(takerAssetFillAmount);
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.marketSellOrdersNoThrowAsync(
+                orders,
+                validTakerAddress,
+                {
+                    takerAssetFillAmount: cumulativeTakerAssetFillAmount,
+                    // HACK(albrow): We need to hardcode the gas estimate here because
+                    // the Geth gas estimator doesn't work with the way we use
+                    // delegatecall and swallow errors.
+                    gas: 600000,
+                },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerAssetFillAmount2 = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const makerFeePaid2 = validSignedOrder2.makerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid2 = validSignedOrder2.takerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee.plus(takerFeePaid2);
+            const cumulativeMakerAssetFillAmount = validSignedOrder.makerAssetAmount.plus(makerAssetFillAmount2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(validSignedOrder.makerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(validSignedOrder.takerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(validSignedOrder.makerFee),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount2),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid2),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(cumulativeMakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address]
+                    .add(validSignedOrder.makerFee)
+                    .add(makerFeePaid2)
+                    .add(takerFeePaid),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.marketSellOrdersNoThrowAsync(orders, validTakerAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.marketSellOrdersNoThrowAsync(orders, invalidAddress, {
+                    takerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('marketBuyOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both makers and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const cumulativeTakerAssetFillAmount = validSignedOrder.takerAssetAmount.plus(takerAssetFillAmount);
+            const makerAssetFillAmount2 = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const cumulativeMakerAssetFillAmount = validSignedOrder.makerAssetAmount.plus(makerAssetFillAmount2);
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.marketBuyOrdersAsync(orders, validTakerAddress, {
+                makerAssetFillAmount: cumulativeMakerAssetFillAmount,
+            });
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerFeePaid2 = validSignedOrder2.makerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid2 = validSignedOrder2.takerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee.plus(takerFeePaid2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(validSignedOrder.makerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(validSignedOrder.takerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(validSignedOrder.makerFee),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount2),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid2),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(cumulativeMakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address]
+                    .add(validSignedOrder.makerFee)
+                    .add(makerFeePaid2)
+                    .add(takerFeePaid),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            const dummyMakerAssetFillAmount = new BigNumber(0);
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.marketBuyOrdersAsync(orders, validTakerAddress, {
+                    makerAssetFillAmount: dummyMakerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            const dummyMakerAssetFillAmount = new BigNumber(0);
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.marketBuyOrdersAsync(orders, invalidAddress, {
+                    makerAssetFillAmount: dummyMakerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('marketBuyOrdersNoThrowAsync', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('should transfer the correct amounts and validate both makers/taker when both makers and taker meet the balance threshold', async () => {
+            // Execute a valid fill
+            const orders = [validSignedOrder, validSignedOrder2];
+            const cumulativeTakerAssetFillAmount = validSignedOrder.takerAssetAmount.plus(takerAssetFillAmount);
+            const makerAssetFillAmount2 = takerAssetFillAmount
+                .times(validSignedOrder.makerAssetAmount)
+                .dividedToIntegerBy(validSignedOrder.takerAssetAmount);
+            const cumulativeMakerAssetFillAmount = validSignedOrder.makerAssetAmount.plus(makerAssetFillAmount2);
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.marketBuyOrdersNoThrowAsync(
+                orders,
+                validTakerAddress,
+                {
+                    makerAssetFillAmount: cumulativeMakerAssetFillAmount,
+                    // HACK(albrow): We need to hardcode the gas estimate here because
+                    // the Geth gas estimator doesn't work with the way we use
+                    // delegatecall and swallow errors.
+                    gas: 600000,
+                },
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                validSignedOrder.makerAddress,
+                validSignedOrder2.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            const makerFeePaid2 = validSignedOrder2.makerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid2 = validSignedOrder2.takerFee
+                .times(makerAssetFillAmount2)
+                .dividedToIntegerBy(validSignedOrder2.makerAssetAmount);
+            const takerFeePaid = validSignedOrder.takerFee.plus(takerFeePaid2);
+            // Maker #1
+            expect(newBalances[validMakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultMakerAssetAddress].minus(validSignedOrder.makerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][defaultTakerAssetAddress].add(validSignedOrder.takerAssetAmount),
+            );
+            expect(newBalances[validMakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress][zrxToken.address].minus(validSignedOrder.makerFee),
+            );
+            // Maker #2
+            expect(newBalances[validMakerAddress2][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultMakerAssetAddress].minus(makerAssetFillAmount2),
+            );
+            expect(newBalances[validMakerAddress2][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][defaultTakerAssetAddress].add(takerAssetFillAmount),
+            );
+            expect(newBalances[validMakerAddress2][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validMakerAddress2][zrxToken.address].minus(makerFeePaid2),
+            );
+            // Taker
+            expect(newBalances[validTakerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultTakerAssetAddress].minus(cumulativeTakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(cumulativeMakerAssetFillAmount),
+            );
+            expect(newBalances[validTakerAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address].minus(takerFeePaid),
+            );
+            // Fee recipient
+            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address]
+                    .add(validSignedOrder.makerFee)
+                    .add(makerFeePaid2)
+                    .add(takerFeePaid),
+            );
+        });
+        it('should revert if one maker does not meet the balance threshold', async () => {
+            // Create order set with one non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                makerAddress: invalidAddress,
+            });
+            const orders = [validSignedOrder, signedOrderWithBadMakerAddress];
+            // Execute transaction
+            const dummyMakerAssetFillAmount = new BigNumber(0);
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.marketBuyOrdersNoThrowAsync(orders, validTakerAddress, {
+                    makerAssetFillAmount: dummyMakerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            const orders = [validSignedOrder, validSignedOrder2];
+            const dummyMakerAssetFillAmount = new BigNumber(0);
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.marketBuyOrdersNoThrowAsync(orders, invalidAddress, {
+                    makerAssetFillAmount: dummyMakerAssetFillAmount,
+                }),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('matchOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('Should transfer correct amounts when both makers and taker meet the balance threshold', async () => {
+            // Test values/results taken from Match Orders test:
+            // 'Should transfer correct amounts when right order is fully filled and values pass isRoundingErrorFloor but fail isRoundingErrorCeil'
+            // Create orders to match
+            const signedOrderLeft = await orderFactory.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(17), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(98), 0),
+                makerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 18),
+                takerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 18),
+                feeRecipientAddress,
+            });
+            const signedOrderRight = await orderFactory2.newSignedOrderAsync({
+                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultTakerAssetAddress),
+                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultMakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                makerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 18),
+                takerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 18),
+                feeRecipientAddress,
+            });
+            // Compute expected transfer amounts
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.4705882352941176'), 16), // 76.47%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.5306122448979591'), 16), // 76.53%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            const txReceipt = await erc721TakerBalanceThresholdWrapper.matchOrdersAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                validTakerAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses = [
+                signedOrderLeft.makerAddress,
+                signedOrderRight.makerAddress,
+                validTakerAddress,
+            ];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check balances
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            expect(
+                newBalances[signedOrderLeft.makerAddress][defaultMakerAssetAddress],
+                'Checking left maker egress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderLeft.makerAddress][defaultMakerAssetAddress].sub(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(
+                newBalances[signedOrderRight.makerAddress][defaultTakerAssetAddress],
+                'Checking right maker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderRight.makerAddress][defaultTakerAssetAddress].sub(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(
+                newBalances[validTakerAddress][defaultMakerAssetAddress],
+                'Checking taker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][defaultMakerAssetAddress].add(
+                    expectedTransferAmounts.amountReceivedByTaker,
+                ),
+            );
+            expect(
+                newBalances[signedOrderLeft.makerAddress][defaultTakerAssetAddress],
+                'Checking left maker ingress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderLeft.makerAddress][defaultTakerAssetAddress].add(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(
+                newBalances[signedOrderRight.makerAddress][defaultMakerAssetAddress],
+                'Checking right maker egress ERC20 account balance',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderRight.makerAddress][defaultMakerAssetAddress].add(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            // Paid fees
+            expect(
+                newBalances[signedOrderLeft.makerAddress][zrxToken.address],
+                'Checking left maker egress ERC20 account fees',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderLeft.makerAddress][zrxToken.address].minus(
+                    expectedTransferAmounts.feePaidByLeftMaker,
+                ),
+            );
+            expect(
+                newBalances[signedOrderRight.makerAddress][zrxToken.address],
+                'Checking right maker egress ERC20 account fees',
+            ).to.be.bignumber.equal(
+                erc20Balances[signedOrderRight.makerAddress][zrxToken.address].minus(
+                    expectedTransferAmounts.feePaidByRightMaker,
+                ),
+            );
+            expect(
+                newBalances[validTakerAddress][zrxToken.address],
+                'Checking taker egress ERC20 account fees',
+            ).to.be.bignumber.equal(
+                erc20Balances[validTakerAddress][zrxToken.address]
+                    .minus(expectedTransferAmounts.feePaidByTakerLeft)
+                    .sub(expectedTransferAmounts.feePaidByTakerRight),
+            );
+            // Received fees
+            expect(
+                newBalances[signedOrderLeft.feeRecipientAddress][zrxToken.address],
+                'Checking left fee recipient ingress ERC20 account fees',
+            ).to.be.bignumber.equal(
+                erc20Balances[feeRecipientAddress][zrxToken.address]
+                    .add(expectedTransferAmounts.feePaidByLeftMaker)
+                    .add(expectedTransferAmounts.feePaidByRightMaker)
+                    .add(expectedTransferAmounts.feePaidByTakerLeft)
+                    .add(expectedTransferAmounts.feePaidByTakerRight),
+            );
+        });
+        it('should revert if left maker does not meet the balance threshold', async () => {
+            // Create signed order with non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: erc721BalanceThresholdFilterInstance.address,
+                makerAddress: invalidAddress,
+            });
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.matchOrdersAsync(
+                    validSignedOrder,
+                    signedOrderWithBadMakerAddress,
+                    validTakerAddress,
+                ),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if right maker does not meet the balance threshold', async () => {
+            // Create signed order with non-valid maker address
+            const signedOrderWithBadMakerAddress = await orderFactory.newSignedOrderAsync({
+                senderAddress: erc721BalanceThresholdFilterInstance.address,
+                makerAddress: invalidAddress,
+            });
+            // Execute transaction
+            return expectTransactionFailedAsync(
+                erc721TakerBalanceThresholdWrapper.matchOrdersAsync(
+                    signedOrderWithBadMakerAddress,
+                    validSignedOrder,
+                    validTakerAddress,
+                ),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+        it('should revert if taker does not meet the balance threshold', async () => {
+            return expectTransactionFailedAsync(
+                erc721NonValidBalanceThresholdWrapper.matchOrdersAsync(
+                    validSignedOrder,
+                    validSignedOrder,
+                    invalidAddress,
+                ),
+                RevertReason.AtLeastOneAddressDoesNotMeetBalanceThreshold,
+            );
+        });
+    });
+
+    describe('cancelOrder', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+            validSignedOrder = await orderFactory.newSignedOrderAsync();
+            validSignedOrder2 = await orderFactory2.newSignedOrderAsync();
+        });
+        it('Should successfully cancel order if maker meets balance threshold', async () => {
+            // Verify order is not cancelled
+            const orderInfoBeforeCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                validSignedOrder,
+            );
+            expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            // Cancel
+            const txReceipt = await erc721MakerBalanceThresholdWrapper.cancelOrderAsync(
+                validSignedOrder,
+                validSignedOrder.makerAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            const orderInfoAfterCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                validSignedOrder,
+            );
+            expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+        });
+        it('Should successfully cancel order if maker does not meet balance threshold', async () => {
+            // Create order where maker does not meet balance threshold
+            const signedOrderWithBadMakerAddress = await invalidOrderFactory.newSignedOrderAsync({});
+            // Verify order is not cancelled
+            const orderInfoBeforeCancelling = await erc721NonValidBalanceThresholdWrapper.getOrderInfoAsync(
+                signedOrderWithBadMakerAddress,
+            );
+            expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            // Cancel
+            const txReceipt = await erc721NonValidBalanceThresholdWrapper.cancelOrderAsync(
+                signedOrderWithBadMakerAddress,
+                signedOrderWithBadMakerAddress.makerAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            const orderInfoAfterCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                signedOrderWithBadMakerAddress,
+            );
+            expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+        });
+    });
+
+    describe('batchCancelOrders', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+        });
+        it('Should successfully batch cancel orders if maker meets balance threshold', async () => {
+            // Create orders to cancel
+            const validSignedOrders = [
+                await orderFactory.newSignedOrderAsync(),
+                await orderFactory.newSignedOrderAsync(),
+                await orderFactory.newSignedOrderAsync(),
+            ];
+            // Verify orders are not cancelled
+            _.each(validSignedOrders, async signedOrder => {
+                const orderInfoBeforeCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            });
+            // Cancel
+            const txReceipt = await erc721MakerBalanceThresholdWrapper.batchCancelOrdersAsync(
+                validSignedOrders,
+                validSignedOrders[0].makerAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            _.each(validSignedOrders, async signedOrder => {
+                const orderInfoAfterCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+            });
+        });
+        it('Should successfully batch cancel order if maker does not meet balance threshold', async () => {
+            // Create orders to cancel
+            const invalidSignedOrders = [
+                await invalidOrderFactory.newSignedOrderAsync(),
+                await invalidOrderFactory.newSignedOrderAsync(),
+                await invalidOrderFactory.newSignedOrderAsync(),
+            ];
+            // Verify orders are not cancelled
+            _.each(invalidSignedOrders, async signedOrder => {
+                const orderInfoBeforeCancelling = await erc721NonValidBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            });
+            // Cancel
+            const txReceipt = await erc721NonValidBalanceThresholdWrapper.batchCancelOrdersAsync(
+                invalidSignedOrders,
+                invalidAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            _.each(invalidSignedOrders, async signedOrder => {
+                const orderInfoAfterCancelling = await erc721NonValidBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+            });
+        });
+    });
+
+    describe('cancelOrdersUpTo', () => {
+        beforeEach(async () => {
+            erc20Balances = await erc20Wrapper.getBalancesAsync();
+        });
+        it('Should successfully batch cancel orders if maker meets balance threshold', async () => {
+            // Create orders to cancel
+            const validSignedOrders = [
+                await orderFactory.newSignedOrderAsync({ salt: new BigNumber(0) }),
+                await orderFactory.newSignedOrderAsync({ salt: new BigNumber(1) }),
+                await orderFactory.newSignedOrderAsync({ salt: new BigNumber(2) }),
+            ];
+            // Verify orders are not cancelled
+            _.each(validSignedOrders, async signedOrder => {
+                const orderInfoBeforeCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            });
+            // Cancel
+            const cancelOrdersUpToThisSalt = new BigNumber(1);
+            const txReceipt = await erc721MakerBalanceThresholdWrapper.cancelOrdersUpToAsync(
+                cancelOrdersUpToThisSalt,
+                validSignedOrders[0].makerAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            _.each(validSignedOrders, async (signedOrder, salt: number) => {
+                const orderInfoAfterCancelling = await erc721MakerBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                const saltAsBigNumber = new BigNumber(salt);
+                if (saltAsBigNumber.lessThanOrEqualTo(cancelOrdersUpToThisSalt)) {
+                    return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+                } else {
+                    return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+                }
+            });
+        });
+        it('Should successfully batch cancel order if maker does not meet balance threshold', async () => {
+            // Create orders to cancel
+            const invalidSignedOrders = [
+                await invalidOrderFactory.newSignedOrderAsync({ salt: new BigNumber(0) }),
+                await invalidOrderFactory.newSignedOrderAsync({ salt: new BigNumber(1) }),
+                await invalidOrderFactory.newSignedOrderAsync({ salt: new BigNumber(2) }),
+            ];
+            // Verify orders are not cancelled
+            _.each(invalidSignedOrders, async signedOrder => {
+                const orderInfoBeforeCancelling = await erc721NonValidBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                return expect(orderInfoBeforeCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+            });
+            // Cancel
+            const cancelOrdersUpToThisSalt = new BigNumber(1);
+            const txReceipt = await erc721NonValidBalanceThresholdWrapper.cancelOrdersUpToAsync(
+                cancelOrdersUpToThisSalt,
+                invalidAddress,
+            );
+            // Assert validated addresses
+            const expectedValidatedAddresseses: string[] = [];
+            await assertValidatedAddressesLog(txReceipt, expectedValidatedAddresseses);
+            // Check that order was cancelled
+            _.each(invalidSignedOrders, async (signedOrder, salt: number) => {
+                const orderInfoAfterCancelling = await erc721NonValidBalanceThresholdWrapper.getOrderInfoAsync(
+                    signedOrder,
+                );
+                const saltAsBigNumber = new BigNumber(salt);
+                if (saltAsBigNumber.lessThanOrEqualTo(cancelOrdersUpToThisSalt)) {
+                    return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.CANCELLED);
+                } else {
+                    return expect(orderInfoAfterCancelling.orderStatus).to.be.equal(OrderStatus.FILLABLE);
+                }
+            });
+        });
+    });
+});
+// tslint:disable:max-file-line-count
+// tslint:enable:no-unnecessary-type-assertion
diff --git a/contracts/extensions/test/extensions/forwarder.ts b/contracts/extensions/test/extensions/forwarder.ts
index 4027f493d..69939ed04 100644
--- a/contracts/extensions/test/extensions/forwarder.ts
+++ b/contracts/extensions/test/extensions/forwarder.ts
@@ -48,7 +48,6 @@ describe(ContractName.Forwarder, () => {
     let owner: string;
     let takerAddress: string;
     let feeRecipientAddress: string;
-    let otherAddress: string;
     let defaultMakerAssetAddress: string;
     let zrxAssetData: string;
     let wethAssetData: string;
@@ -78,7 +77,7 @@ describe(ContractName.Forwarder, () => {
     before(async () => {
         await blockchainLifecycle.startAsync();
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress, otherAddress] = accounts);
+        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress] = accounts);
 
         const txHash = await web3Wrapper.sendTransactionAsync({ from: accounts[0], to: accounts[0], value: 0 });
         const transaction = await web3Wrapper.getTransactionByHashAsync(txHash);
diff --git a/contracts/extensions/test/extensions/order_matcher.ts b/contracts/extensions/test/extensions/order_matcher.ts
new file mode 100644
index 000000000..acb46ced4
--- /dev/null
+++ b/contracts/extensions/test/extensions/order_matcher.ts
@@ -0,0 +1,818 @@
+import {
+    artifacts as protocolArtifacts,
+    ERC20ProxyContract,
+    ERC20Wrapper,
+    ERC721ProxyContract,
+    ExchangeContract,
+    ExchangeFillEventArgs,
+    ExchangeWrapper,
+} from '@0x/contracts-protocol';
+import {
+    chaiSetup,
+    constants,
+    ERC20BalancesByOwner,
+    expectContractCreationFailedAsync,
+    expectTransactionFailedAsync,
+    LogDecoder,
+    OrderFactory,
+    provider,
+    sendTransactionResult,
+    txDefaults,
+    web3Wrapper,
+} from '@0x/contracts-test-utils';
+import { artifacts as tokenArtifacts, DummyERC20TokenContract, DummyERC721TokenContract } from '@0x/contracts-tokens';
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import { assetDataUtils } from '@0x/order-utils';
+import { RevertReason } from '@0x/types';
+import { BigNumber } from '@0x/utils';
+import { Web3Wrapper } from '@0x/web3-wrapper';
+import * as chai from 'chai';
+import { LogWithDecodedArgs } from 'ethereum-types';
+import * as _ from 'lodash';
+
+import { OrderMatcherContract } from '../../generated-wrappers/order_matcher';
+import { artifacts } from '../../src/artifacts';
+
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+chaiSetup.configure();
+const expect = chai.expect;
+// tslint:disable:no-unnecessary-type-assertion
+describe('OrderMatcher', () => {
+    let makerAddressLeft: string;
+    let makerAddressRight: string;
+    let owner: string;
+    let takerAddress: string;
+    let feeRecipientAddressLeft: string;
+    let feeRecipientAddressRight: string;
+
+    let erc20TokenA: DummyERC20TokenContract;
+    let erc20TokenB: DummyERC20TokenContract;
+    let zrxToken: DummyERC20TokenContract;
+    let exchange: ExchangeContract;
+    let erc20Proxy: ERC20ProxyContract;
+    let erc721Proxy: ERC721ProxyContract;
+    let orderMatcher: OrderMatcherContract;
+
+    let erc20BalancesByOwner: ERC20BalancesByOwner;
+    let exchangeWrapper: ExchangeWrapper;
+    let erc20Wrapper: ERC20Wrapper;
+    let orderFactoryLeft: OrderFactory;
+    let orderFactoryRight: OrderFactory;
+
+    let leftMakerAssetData: string;
+    let leftTakerAssetData: string;
+    let defaultERC20MakerAssetAddress: string;
+    let defaultERC20TakerAssetAddress: string;
+
+    before(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    after(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    before(async () => {
+        // Create accounts
+        const accounts = await web3Wrapper.getAvailableAddressesAsync();
+        // Hack(albrow): Both Prettier and TSLint insert a trailing comma below
+        // but that is invalid syntax as of TypeScript version >= 2.8. We don't
+        // have the right fine-grained configuration options in TSLint,
+        // Prettier, or TypeScript, to reconcile this, so we will just have to
+        // wait for them to sort it out. We disable TSLint and Prettier for
+        // this part of the code for now. This occurs several times in this
+        // file. See https://github.com/prettier/prettier/issues/4624.
+        // prettier-ignore
+        const usedAddresses = ([
+            owner,
+            makerAddressLeft,
+            makerAddressRight,
+            takerAddress,
+            feeRecipientAddressLeft,
+            // tslint:disable-next-line:trailing-comma
+            feeRecipientAddressRight
+        ] = _.slice(accounts, 0, 6));
+        // Create wrappers
+        erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
+        // Deploy ERC20 token & ERC20 proxy
+        const numDummyErc20ToDeploy = 3;
+        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
+        erc20Proxy = await erc20Wrapper.deployProxyAsync();
+        await erc20Wrapper.setBalancesAndAllowancesAsync();
+        // Deploy ERC721 proxy
+        erc721Proxy = await ERC721ProxyContract.deployFrom0xArtifactAsync(
+            protocolArtifacts.ERC721Proxy,
+            provider,
+            txDefaults,
+        );
+        // Depoy exchange
+        exchange = await ExchangeContract.deployFrom0xArtifactAsync(
+            protocolArtifacts.Exchange,
+            provider,
+            txDefaults,
+            assetDataUtils.encodeERC20AssetData(zrxToken.address),
+        );
+        exchangeWrapper = new ExchangeWrapper(exchange, provider);
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, owner);
+        // Authorize ERC20 trades by exchange
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, {
+                from: owner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        // Deploy OrderMatcher
+        orderMatcher = await OrderMatcherContract.deployFrom0xArtifactAsync(
+            artifacts.OrderMatcher,
+            provider,
+            txDefaults,
+            exchange.address,
+        );
+        // Set default addresses
+        defaultERC20MakerAssetAddress = erc20TokenA.address;
+        defaultERC20TakerAssetAddress = erc20TokenB.address;
+        leftMakerAssetData = assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress);
+        leftTakerAssetData = assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress);
+        // Set OrderMatcher balances and allowances
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await erc20TokenA.setBalance.sendTransactionAsync(orderMatcher.address, constants.INITIAL_ERC20_BALANCE, {
+                from: owner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await erc20TokenB.setBalance.sendTransactionAsync(orderMatcher.address, constants.INITIAL_ERC20_BALANCE, {
+                from: owner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await orderMatcher.approveAssetProxy.sendTransactionAsync(
+                leftMakerAssetData,
+                constants.INITIAL_ERC20_ALLOWANCE,
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await orderMatcher.approveAssetProxy.sendTransactionAsync(
+                leftTakerAssetData,
+                constants.INITIAL_ERC20_ALLOWANCE,
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        // Create default order parameters
+        const defaultOrderParamsLeft = {
+            ...constants.STATIC_ORDER_PARAMS,
+            makerAddress: makerAddressLeft,
+            exchangeAddress: exchange.address,
+            makerAssetData: leftMakerAssetData,
+            takerAssetData: leftTakerAssetData,
+            feeRecipientAddress: feeRecipientAddressLeft,
+            makerFee: constants.ZERO_AMOUNT,
+            takerFee: constants.ZERO_AMOUNT,
+        };
+        const defaultOrderParamsRight = {
+            ...constants.STATIC_ORDER_PARAMS,
+            makerAddress: makerAddressRight,
+            exchangeAddress: exchange.address,
+            makerAssetData: leftTakerAssetData,
+            takerAssetData: leftMakerAssetData,
+            feeRecipientAddress: feeRecipientAddressRight,
+            makerFee: constants.ZERO_AMOUNT,
+            takerFee: constants.ZERO_AMOUNT,
+        };
+        const privateKeyLeft = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(makerAddressLeft)];
+        orderFactoryLeft = new OrderFactory(privateKeyLeft, defaultOrderParamsLeft);
+        const privateKeyRight = constants.TESTRPC_PRIVATE_KEYS[accounts.indexOf(makerAddressRight)];
+        orderFactoryRight = new OrderFactory(privateKeyRight, defaultOrderParamsRight);
+    });
+    beforeEach(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    afterEach(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    describe('constructor', () => {
+        it('should revert if assetProxy is unregistered', async () => {
+            const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
+                protocolArtifacts.Exchange,
+                provider,
+                txDefaults,
+                constants.NULL_BYTES,
+            );
+            return expectContractCreationFailedAsync(
+                (OrderMatcherContract.deployFrom0xArtifactAsync(
+                    artifacts.OrderMatcher,
+                    provider,
+                    txDefaults,
+                    exchangeInstance.address,
+                ) as any) as sendTransactionResult,
+                RevertReason.UnregisteredAssetProxy,
+            );
+        });
+    });
+    describe('matchOrders', () => {
+        beforeEach(async () => {
+            erc20BalancesByOwner = await erc20Wrapper.getBalancesAsync();
+        });
+        it('should revert if not called by owner', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await expectTransactionFailedAsync(
+                web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: takerAddress,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                RevertReason.OnlyContractOwner,
+            );
+        });
+        it('should transfer the correct amounts when orders completely fill each other', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: signedOrderLeft.makerAssetAmount,
+                amountBoughtByLeftMaker: signedOrderLeft.takerAssetAmount,
+                // Right Maker
+                amountSoldByRightMaker: signedOrderRight.makerAssetAmount,
+                amountBoughtByRightMaker: signedOrderRight.takerAssetAmount,
+                // Taker
+                leftMakerAssetSpreadAmount: signedOrderLeft.makerAssetAmount.minus(signedOrderRight.takerAssetAmount),
+            };
+            const initialLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const newErc20Balances = await erc20Wrapper.getBalancesAsync();
+            expect(newErc20Balances[makerAddressLeft][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20MakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20TakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressLeft][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20TakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20MakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            expect(newLeftMakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftMakerAssetTakerBalance.plus(expectedTransferAmounts.leftMakerAssetSpreadAmount),
+            );
+        });
+        it('should transfer the correct amounts when orders completely fill each other and taker doesnt take a profit', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: signedOrderLeft.makerAssetAmount,
+                amountBoughtByLeftMaker: signedOrderLeft.takerAssetAmount,
+                // Right Maker
+                amountSoldByRightMaker: signedOrderRight.makerAssetAmount,
+                amountBoughtByRightMaker: signedOrderRight.takerAssetAmount,
+            };
+            const initialLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const newErc20Balances = await erc20Wrapper.getBalancesAsync();
+            expect(newErc20Balances[makerAddressLeft][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20MakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20TakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressLeft][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20TakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20MakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            expect(newLeftMakerAssetTakerBalance).to.be.bignumber.equal(initialLeftMakerAssetTakerBalance);
+        });
+        it('should transfer the correct amounts when left order is completely filled and right order would be partially filled', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(20), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: signedOrderLeft.makerAssetAmount,
+                amountBoughtByLeftMaker: signedOrderLeft.takerAssetAmount,
+                // Right Maker
+                amountSoldByRightMaker: signedOrderRight.makerAssetAmount,
+                amountBoughtByRightMaker: signedOrderRight.takerAssetAmount,
+                // Taker
+                leftMakerAssetSpreadAmount: signedOrderLeft.makerAssetAmount.minus(signedOrderRight.takerAssetAmount),
+                leftTakerAssetSpreadAmount: signedOrderRight.makerAssetAmount.minus(signedOrderLeft.takerAssetAmount),
+            };
+            const initialLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const initialLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            // Match signedOrderLeft with signedOrderRight
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const newLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            const newErc20Balances = await erc20Wrapper.getBalancesAsync();
+            expect(newErc20Balances[makerAddressLeft][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20MakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20TakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressLeft][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20TakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20MakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            expect(newLeftMakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftMakerAssetTakerBalance.plus(expectedTransferAmounts.leftMakerAssetSpreadAmount),
+            );
+            expect(newLeftTakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftTakerAssetTakerBalance.plus(expectedTransferAmounts.leftTakerAssetSpreadAmount),
+            );
+        });
+        it('should not call fillOrder when rightOrder is completely filled after matchOrders call and orders were never partially filled', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            const logDecoder = new LogDecoder(web3Wrapper, { ...artifacts, ...tokenArtifacts, ...protocolArtifacts });
+            const txReceipt = await logDecoder.getTxWithDecodedLogsAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+            );
+            const fillLogs = _.filter(
+                txReceipt.logs,
+                log => (log as LogWithDecodedArgs<ExchangeFillEventArgs>).event === 'Fill',
+            );
+            // Only 2 Fill logs should exist for `matchOrders` call. `fillOrder` should not have been called and should not have emitted a Fill event.
+            expect(fillLogs.length).to.be.equal(2);
+        });
+        it('should not call fillOrder when rightOrder is completely filled after matchOrders call and orders were initially partially filled', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 18),
+            });
+            await exchangeWrapper.fillOrderAsync(signedOrderLeft, takerAddress, {
+                takerAssetFillAmount: signedOrderLeft.takerAssetAmount.dividedToIntegerBy(5),
+            });
+            await exchangeWrapper.fillOrderAsync(signedOrderRight, takerAddress, {
+                takerAssetFillAmount: signedOrderRight.takerAssetAmount.dividedToIntegerBy(5),
+            });
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            const logDecoder = new LogDecoder(web3Wrapper, { ...artifacts, ...tokenArtifacts, ...protocolArtifacts });
+            const txReceipt = await logDecoder.getTxWithDecodedLogsAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+            );
+            const fillLogs = _.filter(
+                txReceipt.logs,
+                log => (log as LogWithDecodedArgs<ExchangeFillEventArgs>).event === 'Fill',
+            );
+            // Only 2 Fill logs should exist for `matchOrders` call. `fillOrder` should not have been called and should not have emitted a Fill event.
+            expect(fillLogs.length).to.be.equal(2);
+        });
+        it('should only take a spread in rightMakerAsset if entire leftMakerAssetSpread amount can be used to fill rightOrder after matchOrders call', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(0.9), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(990), 18),
+            });
+            const initialLeftMakerAssetSpreadAmount = Web3Wrapper.toBaseUnitAmount(new BigNumber(1.09), 18);
+            const leftTakerAssetSpreadAmount = initialLeftMakerAssetSpreadAmount
+                .times(signedOrderRight.makerAssetAmount)
+                .dividedToIntegerBy(signedOrderRight.takerAssetAmount);
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: signedOrderLeft.makerAssetAmount,
+                amountBoughtByLeftMaker: signedOrderLeft.takerAssetAmount,
+                // Right Maker
+                amountSoldByRightMaker: signedOrderLeft.takerAssetAmount.plus(leftTakerAssetSpreadAmount),
+                amountBoughtByRightMaker: signedOrderLeft.makerAssetAmount,
+                // Taker
+                leftMakerAssetSpreadAmount: constants.ZERO_AMOUNT,
+                leftTakerAssetSpreadAmount,
+            };
+            const initialLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const initialLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            // Match signedOrderLeft with signedOrderRight
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const newLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            const newErc20Balances = await erc20Wrapper.getBalancesAsync();
+            expect(newErc20Balances[makerAddressLeft][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20MakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20TakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressLeft][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20TakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20MakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            expect(newLeftMakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftMakerAssetTakerBalance.plus(expectedTransferAmounts.leftMakerAssetSpreadAmount),
+            );
+            expect(newLeftTakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftTakerAssetTakerBalance.plus(expectedTransferAmounts.leftTakerAssetSpreadAmount),
+            );
+        });
+        it("should succeed if rightOrder's makerAssetData and takerAssetData are not provided", async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(20), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+            });
+            // Match signedOrderLeft with signedOrderRight
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: signedOrderLeft.makerAssetAmount,
+                amountBoughtByLeftMaker: signedOrderLeft.takerAssetAmount,
+                // Right Maker
+                amountSoldByRightMaker: signedOrderRight.makerAssetAmount,
+                amountBoughtByRightMaker: signedOrderRight.takerAssetAmount,
+                // Taker
+                leftMakerAssetSpreadAmount: signedOrderLeft.makerAssetAmount.minus(signedOrderRight.takerAssetAmount),
+                leftTakerAssetSpreadAmount: signedOrderRight.makerAssetAmount.minus(signedOrderLeft.takerAssetAmount),
+            };
+            const initialLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const initialLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            // Match signedOrderLeft with signedOrderRight
+            signedOrderRight.makerAssetData = constants.NULL_BYTES;
+            signedOrderRight.takerAssetData = constants.NULL_BYTES;
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newLeftMakerAssetTakerBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            const newLeftTakerAssetTakerBalance = await erc20TokenB.balanceOf.callAsync(orderMatcher.address);
+            const newErc20Balances = await erc20Wrapper.getBalancesAsync();
+            expect(newErc20Balances[makerAddressLeft][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20MakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20TakerAssetAddress].minus(
+                    expectedTransferAmounts.amountSoldByRightMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressLeft][defaultERC20TakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressLeft][defaultERC20TakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByLeftMaker,
+                ),
+            );
+            expect(newErc20Balances[makerAddressRight][defaultERC20MakerAssetAddress]).to.be.bignumber.equal(
+                erc20BalancesByOwner[makerAddressRight][defaultERC20MakerAssetAddress].plus(
+                    expectedTransferAmounts.amountBoughtByRightMaker,
+                ),
+            );
+            expect(newLeftMakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftMakerAssetTakerBalance.plus(expectedTransferAmounts.leftMakerAssetSpreadAmount),
+            );
+            expect(newLeftTakerAssetTakerBalance).to.be.bignumber.equal(
+                initialLeftTakerAssetTakerBalance.plus(expectedTransferAmounts.leftTakerAssetSpreadAmount),
+            );
+        });
+        it('should revert with the correct reason if matchOrders call reverts', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+            });
+            signedOrderRight.signature = `0xff${signedOrderRight.signature.slice(4)}`;
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await expectTransactionFailedAsync(
+                web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                RevertReason.InvalidOrderSignature,
+            );
+        });
+        it('should revert with the correct reason if fillOrder call reverts', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(5), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 18),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(20), 18),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 18),
+            });
+            // Matcher will not have enough allowance to fill rightOrder
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.approveAssetProxy.sendTransactionAsync(leftMakerAssetData, constants.ZERO_AMOUNT, {
+                    from: owner,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const data = exchange.matchOrders.getABIEncodedTransactionData(
+                signedOrderLeft,
+                signedOrderRight,
+                signedOrderLeft.signature,
+                signedOrderRight.signature,
+            );
+            await expectTransactionFailedAsync(
+                web3Wrapper.sendTransactionAsync({
+                    data,
+                    to: orderMatcher.address,
+                    from: owner,
+                    gas: constants.MAX_MATCH_ORDERS_GAS,
+                }),
+                RevertReason.TransferFailed,
+            );
+        });
+    });
+    describe('withdrawAsset', () => {
+        it('should allow owner to withdraw ERC20 tokens', async () => {
+            const erc20AWithdrawAmount = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            expect(erc20AWithdrawAmount).to.be.bignumber.gt(constants.ZERO_AMOUNT);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.withdrawAsset.sendTransactionAsync(leftMakerAssetData, erc20AWithdrawAmount, {
+                    from: owner,
+                }),
+            );
+            const newBalance = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            expect(newBalance).to.be.bignumber.equal(constants.ZERO_AMOUNT);
+        });
+        it('should allow owner to withdraw ERC721 tokens', async () => {
+            const erc721Token = await DummyERC721TokenContract.deployFrom0xArtifactAsync(
+                tokenArtifacts.DummyERC721Token,
+                provider,
+                txDefaults,
+                constants.DUMMY_TOKEN_NAME,
+                constants.DUMMY_TOKEN_SYMBOL,
+            );
+            const tokenId = new BigNumber(1);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await erc721Token.mint.sendTransactionAsync(orderMatcher.address, tokenId, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const assetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, tokenId);
+            const withdrawAmount = new BigNumber(1);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.withdrawAsset.sendTransactionAsync(assetData, withdrawAmount, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const erc721Owner = await erc721Token.ownerOf.callAsync(tokenId);
+            expect(erc721Owner).to.be.equal(owner);
+        });
+        it('should revert if not called by owner', async () => {
+            const erc20AWithdrawAmount = await erc20TokenA.balanceOf.callAsync(orderMatcher.address);
+            expect(erc20AWithdrawAmount).to.be.bignumber.gt(constants.ZERO_AMOUNT);
+            await expectTransactionFailedAsync(
+                orderMatcher.withdrawAsset.sendTransactionAsync(leftMakerAssetData, erc20AWithdrawAmount, {
+                    from: takerAddress,
+                }),
+                RevertReason.OnlyContractOwner,
+            );
+        });
+    });
+    describe('approveAssetProxy', () => {
+        it('should be able to set an allowance for ERC20 tokens', async () => {
+            const allowance = new BigNumber(55465465426546);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.approveAssetProxy.sendTransactionAsync(leftMakerAssetData, allowance, {
+                    from: owner,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const newAllowance = await erc20TokenA.allowance.callAsync(orderMatcher.address, erc20Proxy.address);
+            expect(newAllowance).to.be.bignumber.equal(allowance);
+        });
+        it('should be able to approve an ERC721 token by passing in allowance = 1', async () => {
+            const erc721Token = await DummyERC721TokenContract.deployFrom0xArtifactAsync(
+                tokenArtifacts.DummyERC721Token,
+                provider,
+                txDefaults,
+                constants.DUMMY_TOKEN_NAME,
+                constants.DUMMY_TOKEN_SYMBOL,
+            );
+            const assetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, constants.ZERO_AMOUNT);
+            const allowance = new BigNumber(1);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.approveAssetProxy.sendTransactionAsync(assetData, allowance, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const isApproved = await erc721Token.isApprovedForAll.callAsync(orderMatcher.address, erc721Proxy.address);
+            expect(isApproved).to.be.equal(true);
+        });
+        it('should be able to approve an ERC721 token by passing in allowance > 1', async () => {
+            const erc721Token = await DummyERC721TokenContract.deployFrom0xArtifactAsync(
+                tokenArtifacts.DummyERC721Token,
+                provider,
+                txDefaults,
+                constants.DUMMY_TOKEN_NAME,
+                constants.DUMMY_TOKEN_SYMBOL,
+            );
+            const assetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, constants.ZERO_AMOUNT);
+            const allowance = new BigNumber(2);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await orderMatcher.approveAssetProxy.sendTransactionAsync(assetData, allowance, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const isApproved = await erc721Token.isApprovedForAll.callAsync(orderMatcher.address, erc721Proxy.address);
+            expect(isApproved).to.be.equal(true);
+        });
+        it('should revert if not called by owner', async () => {
+            const approval = new BigNumber(1);
+            await expectTransactionFailedAsync(
+                orderMatcher.approveAssetProxy.sendTransactionAsync(leftMakerAssetData, approval, {
+                    from: takerAddress,
+                }),
+                RevertReason.OnlyContractOwner,
+            );
+        });
+    });
+});
+// tslint:disable:max-file-line-count
+// tslint:enable:no-unnecessary-type-assertion
diff --git a/contracts/extensions/test/utils/balance_threshold_wrapper.ts b/contracts/extensions/test/utils/balance_threshold_wrapper.ts
new file mode 100644
index 000000000..28a4ef011
--- /dev/null
+++ b/contracts/extensions/test/utils/balance_threshold_wrapper.ts
@@ -0,0 +1,283 @@
+import { artifacts as protocolArtifacts, ExchangeContract } from '@0x/contracts-protocol';
+import {
+    FillResults,
+    formatters,
+    LogDecoder,
+    OrderInfo,
+    orderUtils,
+    TransactionFactory,
+} from '@0x/contracts-test-utils';
+import { artifacts as tokensArtifacts } from '@0x/contracts-tokens';
+import { SignedOrder } from '@0x/types';
+import { BigNumber } from '@0x/utils';
+import { Web3Wrapper } from '@0x/web3-wrapper';
+import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
+import * as _ from 'lodash';
+
+import { BalanceThresholdFilterContract } from '../../generated-wrappers/balance_threshold_filter';
+import { artifacts } from '../../src/artifacts';
+
+export class BalanceThresholdWrapper {
+    private readonly _balanceThresholdFilter: BalanceThresholdFilterContract;
+    private readonly _signerTransactionFactory: TransactionFactory;
+    private readonly _exchange: ExchangeContract;
+    private readonly _web3Wrapper: Web3Wrapper;
+    private readonly _logDecoder: LogDecoder;
+    constructor(
+        balanceThresholdFilter: BalanceThresholdFilterContract,
+        exchangeContract: ExchangeContract,
+        signerTransactionFactory: TransactionFactory,
+        provider: Provider,
+    ) {
+        this._balanceThresholdFilter = balanceThresholdFilter;
+        this._exchange = exchangeContract;
+        this._signerTransactionFactory = signerTransactionFactory;
+        this._web3Wrapper = new Web3Wrapper(provider);
+        this._logDecoder = new LogDecoder(this._web3Wrapper, {
+            ...artifacts,
+            ...tokensArtifacts,
+            ...protocolArtifacts,
+        });
+    }
+    public async fillOrderAsync(
+        signedOrder: SignedOrder,
+        from: string,
+        opts: { takerAssetFillAmount?: BigNumber } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
+        const data = this._exchange.fillOrder.getABIEncodedTransactionData(
+            params.order,
+            params.takerAssetFillAmount,
+            params.signature,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async fillOrKillOrderAsync(
+        signedOrder: SignedOrder,
+        from: string,
+        opts: { takerAssetFillAmount?: BigNumber } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
+        const data = this._exchange.fillOrKillOrder.getABIEncodedTransactionData(
+            params.order,
+            params.takerAssetFillAmount,
+            params.signature,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async fillOrderNoThrowAsync(
+        signedOrder: SignedOrder,
+        from: string,
+        opts: { takerAssetFillAmount?: BigNumber; gas?: number } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
+        const data = this._exchange.fillOrderNoThrow.getABIEncodedTransactionData(
+            params.order,
+            params.takerAssetFillAmount,
+            params.signature,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from, opts.gas);
+        return txReceipt;
+    }
+    public async batchFillOrdersAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { takerAssetFillAmounts?: BigNumber[] } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createBatchFill(orders, opts.takerAssetFillAmounts);
+        const data = this._exchange.batchFillOrders.getABIEncodedTransactionData(
+            params.orders,
+            params.takerAssetFillAmounts,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async batchFillOrKillOrdersAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { takerAssetFillAmounts?: BigNumber[] } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createBatchFill(orders, opts.takerAssetFillAmounts);
+        const data = this._exchange.batchFillOrKillOrders.getABIEncodedTransactionData(
+            params.orders,
+            params.takerAssetFillAmounts,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async batchFillOrdersNoThrowAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { takerAssetFillAmounts?: BigNumber[]; gas?: number } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createBatchFill(orders, opts.takerAssetFillAmounts);
+        const data = this._exchange.batchFillOrKillOrders.getABIEncodedTransactionData(
+            params.orders,
+            params.takerAssetFillAmounts,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from, opts.gas);
+        return txReceipt;
+    }
+    public async marketSellOrdersAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { takerAssetFillAmount: BigNumber },
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createMarketSellOrders(orders, opts.takerAssetFillAmount);
+        const data = this._exchange.marketSellOrders.getABIEncodedTransactionData(
+            params.orders,
+            params.takerAssetFillAmount,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async marketSellOrdersNoThrowAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { takerAssetFillAmount: BigNumber; gas?: number },
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createMarketSellOrders(orders, opts.takerAssetFillAmount);
+        const data = this._exchange.marketSellOrdersNoThrow.getABIEncodedTransactionData(
+            params.orders,
+            params.takerAssetFillAmount,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from, opts.gas);
+        return txReceipt;
+    }
+    public async marketBuyOrdersAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { makerAssetFillAmount: BigNumber },
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createMarketBuyOrders(orders, opts.makerAssetFillAmount);
+        const data = this._exchange.marketBuyOrders.getABIEncodedTransactionData(
+            params.orders,
+            params.makerAssetFillAmount,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async marketBuyOrdersNoThrowAsync(
+        orders: SignedOrder[],
+        from: string,
+        opts: { makerAssetFillAmount: BigNumber; gas?: number },
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createMarketBuyOrders(orders, opts.makerAssetFillAmount);
+        const data = this._exchange.marketBuyOrdersNoThrow.getABIEncodedTransactionData(
+            params.orders,
+            params.makerAssetFillAmount,
+            params.signatures,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from, opts.gas);
+        return txReceipt;
+    }
+    public async cancelOrderAsync(signedOrder: SignedOrder, from: string): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = orderUtils.createCancel(signedOrder);
+        const data = this._exchange.cancelOrder.getABIEncodedTransactionData(params.order);
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async batchCancelOrdersAsync(
+        orders: SignedOrder[],
+        from: string,
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = formatters.createBatchCancel(orders);
+        const data = this._exchange.batchCancelOrders.getABIEncodedTransactionData(params.orders);
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async cancelOrdersUpToAsync(salt: BigNumber, from: string): Promise<TransactionReceiptWithDecodedLogs> {
+        const data = this._exchange.cancelOrdersUpTo.getABIEncodedTransactionData(salt);
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async getTakerAssetFilledAmountAsync(orderHashHex: string): Promise<BigNumber> {
+        const filledAmount = await this._exchange.filled.callAsync(orderHashHex);
+        return filledAmount;
+    }
+    public async isCancelledAsync(orderHashHex: string): Promise<boolean> {
+        const isCancelled = await this._exchange.cancelled.callAsync(orderHashHex);
+        return isCancelled;
+    }
+    public async getOrderEpochAsync(makerAddress: string, senderAddress: string): Promise<BigNumber> {
+        const orderEpoch = await this._exchange.orderEpoch.callAsync(makerAddress, senderAddress);
+        return orderEpoch;
+    }
+    public async getOrderInfoAsync(signedOrder: SignedOrder): Promise<OrderInfo> {
+        const orderInfo = await this._exchange.getOrderInfo.callAsync(signedOrder);
+        return orderInfo;
+    }
+    public async getOrdersInfoAsync(signedOrders: SignedOrder[]): Promise<OrderInfo[]> {
+        const ordersInfo = (await this._exchange.getOrdersInfo.callAsync(signedOrders)) as OrderInfo[];
+        return ordersInfo;
+    }
+    public async matchOrdersAsync(
+        signedOrderLeft: SignedOrder,
+        signedOrderRight: SignedOrder,
+        from: string,
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const params = orderUtils.createMatchOrders(signedOrderLeft, signedOrderRight);
+        const data = await this._exchange.matchOrders.getABIEncodedTransactionData(
+            params.left,
+            params.right,
+            params.leftSignature,
+            params.rightSignature,
+        );
+        const txReceipt = this._executeTransactionAsync(data, from);
+        return txReceipt;
+    }
+    public async getFillOrderResultsAsync(
+        signedOrder: SignedOrder,
+        from: string,
+        opts: { takerAssetFillAmount?: BigNumber } = {},
+    ): Promise<FillResults> {
+        const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
+        const fillResults = await this._exchange.fillOrder.callAsync(
+            params.order,
+            params.takerAssetFillAmount,
+            params.signature,
+            { from },
+        );
+        return fillResults;
+    }
+    public abiEncodeFillOrder(signedOrder: SignedOrder, opts: { takerAssetFillAmount?: BigNumber } = {}): string {
+        const params = orderUtils.createFill(signedOrder, opts.takerAssetFillAmount);
+        const data = this._exchange.fillOrder.getABIEncodedTransactionData(
+            params.order,
+            params.takerAssetFillAmount,
+            params.signature,
+        );
+        return data;
+    }
+    public getBalanceThresholdAddress(): string {
+        return this._balanceThresholdFilter.address;
+    }
+    public getExchangeAddress(): string {
+        return this._exchange.address;
+    }
+    private async _executeTransactionAsync(
+        abiEncodedExchangeTxData: string,
+        from: string,
+        gas?: number,
+    ): Promise<TransactionReceiptWithDecodedLogs> {
+        const signedExchangeTx = this._signerTransactionFactory.newSignedTransaction(abiEncodedExchangeTxData);
+        const txOpts = _.isUndefined(gas) ? { from } : { from, gas };
+        const txHash = await this._balanceThresholdFilter.executeTransaction.sendTransactionAsync(
+            signedExchangeTx.salt,
+            signedExchangeTx.signerAddress,
+            signedExchangeTx.data,
+            signedExchangeTx.signature,
+            txOpts,
+        );
+        const txReceipt = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
+        return txReceipt;
+    }
+}
diff --git a/contracts/extensions/tsconfig.json b/contracts/extensions/tsconfig.json
index a4ce1e002..506c283aa 100644
--- a/contracts/extensions/tsconfig.json
+++ b/contracts/extensions/tsconfig.json
@@ -6,6 +6,11 @@
         "resolveJsonModule": true
     },
     "include": ["./src/**/*", "./test/**/*", "./generated-wrappers/**/*"],
-    "files": ["./generated-artifacts/DutchAuction.json", "./generated-artifacts/Forwarder.json"],
+    "files": [
+        "./generated-artifacts/BalanceThresholdFilter.json",
+        "./generated-artifacts/DutchAuction.json",
+        "./generated-artifacts/Forwarder.json",
+        "./generated-artifacts/OrderMatcher.json"
+    ],
     "exclude": ["./deploy/solc/solc_bin"]
 }
diff --git a/contracts/interfaces/package.json b/contracts/interfaces/package.json
index 4d3e4b7f9..15385a154 100644
--- a/contracts/interfaces/package.json
+++ b/contracts/interfaces/package.json
@@ -10,7 +10,8 @@
         "build": "yarn pre_build && tsc -b",
         "build:ci": "yarn build",
         "pre_build": "run-s compile generate_contract_wrappers",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/contracts/libs/compiler.json b/contracts/libs/compiler.json
index cf7c52a73..349d3063b 100644
--- a/contracts/libs/compiler.json
+++ b/contracts/libs/compiler.json
@@ -18,5 +18,14 @@
             }
         }
     },
-    "contracts": ["TestLibs", "LibOrder", "LibMath", "LibFillResults", "LibAbiEncoder", "LibEIP712"]
+    "contracts": [
+        "TestLibs",
+        "LibOrder",
+        "LibMath",
+        "LibFillResults",
+        "LibAbiEncoder",
+        "LibEIP712",
+        "LibAssetProxyErrors",
+        "LibConstants"
+    ]
 }
diff --git a/contracts/libs/contracts/libs/LibAddressArray.sol b/contracts/libs/contracts/libs/LibAddressArray.sol
new file mode 100644
index 000000000..ccae2ac5f
--- /dev/null
+++ b/contracts/libs/contracts/libs/LibAddressArray.sol
@@ -0,0 +1,84 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "@0x/contracts-utils/contracts/utils/LibBytes/LibBytes.sol";
+
+
+library LibAddressArray {
+
+    /// @dev Append a new address to an array of addresses.
+    ///      The `addressArray` may need to be reallocated to make space
+    ///      for the new address. Because of this we return the resulting
+    ///      memory location of `addressArray`.
+    /// @param addressToAppend  Address to append.
+    /// @return Array of addresses: [... addressArray, addressToAppend]
+    function append(address[] memory addressArray, address addressToAppend) 
+        internal pure
+        returns (address[])
+    {
+        // Get stats on address array and free memory
+        uint256 freeMemPtr = 0;
+        uint256 addressArrayBeginPtr = 0;
+        uint256 addressArrayEndPtr = 0;
+        uint256 addressArrayLength = addressArray.length;
+        uint256 addressArrayMemSizeInBytes = 32 + (32 * addressArrayLength);
+        assembly {
+            freeMemPtr := mload(0x40)
+            addressArrayBeginPtr := addressArray
+            addressArrayEndPtr := add(addressArray, addressArrayMemSizeInBytes)
+        }
+
+        // Cases for `freeMemPtr`:
+        //  `freeMemPtr` == `addressArrayEndPtr`: Nothing occupies memory after `addressArray`
+        //  `freeMemPtr` > `addressArrayEndPtr`: Some value occupies memory after `addressArray`
+        //  `freeMemPtr` < `addressArrayEndPtr`: Memory has not been managed properly.
+        require(
+            freeMemPtr >= addressArrayEndPtr,
+            "INVALID_FREE_MEMORY_PTR"
+        );
+
+        // If free memory begins at the end of `addressArray`
+        // then we can append `addressToAppend` directly.
+        // Otherwise, we must copy the array to free memory
+        // before appending new values to it.
+        if (freeMemPtr > addressArrayEndPtr) {
+            LibBytes.memCopy(freeMemPtr, addressArrayBeginPtr, addressArrayMemSizeInBytes);
+            assembly {
+                addressArray := freeMemPtr
+                addressArrayBeginPtr := addressArray
+            }
+        }
+
+        // Append `addressToAppend`
+        addressArrayLength += 1;
+        addressArrayMemSizeInBytes += 32;
+        addressArrayEndPtr = addressArrayBeginPtr + addressArrayMemSizeInBytes;
+        freeMemPtr = addressArrayEndPtr;
+        assembly {
+            // Store new array length
+            mstore(addressArray, addressArrayLength)
+
+            // Update `freeMemPtr`
+            mstore(0x40, freeMemPtr)
+        }
+        addressArray[addressArrayLength - 1] = addressToAppend;
+        return addressArray;
+    }
+}
diff --git a/contracts/libs/contracts/libs/LibExchangeSelectors.sol b/contracts/libs/contracts/libs/LibExchangeSelectors.sol
new file mode 100644
index 000000000..edb4f9cbd
--- /dev/null
+++ b/contracts/libs/contracts/libs/LibExchangeSelectors.sol
@@ -0,0 +1,152 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract LibExchangeSelectors {
+
+    // solhint-disable max-line-length
+    // allowedValidators
+    bytes4 constant public ALLOWED_VALIDATORS_SELECTOR = 0x7b8e3514;
+    bytes4 constant public ALLOWED_VALIDATORS_SELECTOR_GENERATOR = bytes4(keccak256("allowedValidators(address,address)"));
+
+    // assetProxies
+    bytes4 constant public ASSET_PROXIES_SELECTOR = 0x3fd3c997;
+    bytes4 constant public ASSET_PROXIES_SELECTOR_GENERATOR = bytes4(keccak256("assetProxies(bytes4)"));
+
+    // batchCancelOrders
+    bytes4 constant public BATCH_CANCEL_ORDERS_SELECTOR = 0x4ac14782;
+    bytes4 constant public BATCH_CANCEL_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("batchCancelOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[])"));
+
+    // batchFillOrKillOrders
+    bytes4 constant public BATCH_FILL_OR_KILL_ORDERS_SELECTOR = 0x4d0ae546;
+    bytes4 constant public BATCH_FILL_OR_KILL_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("batchFillOrKillOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])"));
+
+    // batchFillOrders
+    bytes4 constant public BATCH_FILL_ORDERS_SELECTOR = 0x297bb70b;
+    bytes4 constant public BATCH_FILL_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("batchFillOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])"));
+
+    // batchFillOrdersNoThrow
+    bytes4 constant public BATCH_FILL_ORDERS_NO_THROW_SELECTOR = 0x50dde190;
+    bytes4 constant public BATCH_FILL_ORDERS_NO_THROW_SELECTOR_GENERATOR = bytes4(keccak256("batchFillOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])"));
+
+    // cancelOrder
+    bytes4 constant public CANCEL_ORDER_SELECTOR = 0xd46b02c3;
+    bytes4 constant public CANCEL_ORDER_SELECTOR_GENERATOR = bytes4(keccak256("cancelOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes))"));
+
+    // cancelOrdersUpTo
+    bytes4 constant public CANCEL_ORDERS_UP_TO_SELECTOR = 0x4f9559b1;
+    bytes4 constant public CANCEL_ORDERS_UP_TO_SELECTOR_GENERATOR = bytes4(keccak256("cancelOrdersUpTo(uint256)"));
+
+    // cancelled
+    bytes4 constant public CANCELLED_SELECTOR = 0x2ac12622;
+    bytes4 constant public CANCELLED_SELECTOR_GENERATOR = bytes4(keccak256("cancelled(bytes32)"));
+
+    // currentContextAddress
+    bytes4 constant public CURRENT_CONTEXT_ADDRESS_SELECTOR = 0xeea086ba;
+    bytes4 constant public CURRENT_CONTEXT_ADDRESS_SELECTOR_GENERATOR = bytes4(keccak256("currentContextAddress()"));
+
+    // executeTransaction
+    bytes4 constant public EXECUTE_TRANSACTION_SELECTOR = 0xbfc8bfce;
+    bytes4 constant public EXECUTE_TRANSACTION_SELECTOR_GENERATOR = bytes4(keccak256("executeTransaction(uint256,address,bytes,bytes)"));
+
+    // fillOrKillOrder
+    bytes4 constant public FILL_OR_KILL_ORDER_SELECTOR = 0x64a3bc15;
+    bytes4 constant public FILL_OR_KILL_ORDER_SELECTOR_GENERATOR = bytes4(keccak256("fillOrKillOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)"));
+
+    // fillOrder
+    bytes4 constant public FILL_ORDER_SELECTOR = 0xb4be83d5;
+    bytes4 constant public FILL_ORDER_SELECTOR_GENERATOR = bytes4(keccak256("fillOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)"));
+
+    // fillOrderNoThrow
+    bytes4 constant public FILL_ORDER_NO_THROW_SELECTOR = 0x3e228bae;
+    bytes4 constant public FILL_ORDER_NO_THROW_SELECTOR_GENERATOR = bytes4(keccak256("fillOrderNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)"));
+
+    // filled
+    bytes4 constant public FILLED_SELECTOR = 0x288cdc91;
+    bytes4 constant public FILLED_SELECTOR_GENERATOR = bytes4(keccak256("filled(bytes32)"));
+
+    // getAssetProxy
+    bytes4 constant public GET_ASSET_PROXY_SELECTOR = 0x60704108;
+    bytes4 constant public GET_ASSET_PROXY_SELECTOR_GENERATOR = bytes4(keccak256("getAssetProxy(bytes4)"));
+
+    // getOrderInfo
+    bytes4 constant public GET_ORDER_INFO_SELECTOR = 0xc75e0a81;
+    bytes4 constant public GET_ORDER_INFO_SELECTOR_GENERATOR = bytes4(keccak256("getOrderInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes))"));
+
+    // getOrdersInfo
+    bytes4 constant public GET_ORDERS_INFO_SELECTOR = 0x7e9d74dc;
+    bytes4 constant public GET_ORDERS_INFO_SELECTOR_GENERATOR = bytes4(keccak256("getOrdersInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[])"));
+
+    // isValidSignature
+    bytes4 constant public IS_VALID_SIGNATURE_SELECTOR = 0x93634702;
+    bytes4 constant public IS_VALID_SIGNATURE_SELECTOR_GENERATOR = bytes4(keccak256("isValidSignature(bytes32,address,bytes)"));
+
+    // marketBuyOrders
+    bytes4 constant public MARKET_BUY_ORDERS_SELECTOR = 0xe5fa431b;
+    bytes4 constant public MARKET_BUY_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("marketBuyOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])"));
+
+    // marketBuyOrdersNoThrow
+    bytes4 constant public MARKET_BUY_ORDERS_NO_THROW_SELECTOR = 0xa3e20380;
+    bytes4 constant public MARKET_BUY_ORDERS_NO_THROW_SELECTOR_GENERATOR = bytes4(keccak256("marketBuyOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])"));
+
+    // marketSellOrders
+    bytes4 constant public MARKET_SELL_ORDERS_SELECTOR = 0x7e1d9808;
+    bytes4 constant public MARKET_SELL_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("marketSellOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])"));
+
+    // marketSellOrdersNoThrow
+    bytes4 constant public MARKET_SELL_ORDERS_NO_THROW_SELECTOR = 0xdd1c7d18;
+    bytes4 constant public MARKET_SELL_ORDERS_NO_THROW_SELECTOR_GENERATOR = bytes4(keccak256("marketSellOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])"));
+
+    // matchOrders
+    bytes4 constant public MATCH_ORDERS_SELECTOR = 0x3c28d861;
+    bytes4 constant public MATCH_ORDERS_SELECTOR_GENERATOR = bytes4(keccak256("matchOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),(address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),bytes,bytes)"));
+
+    // orderEpoch
+    bytes4 constant public ORDER_EPOCH_SELECTOR = 0xd9bfa73e;
+    bytes4 constant public ORDER_EPOCH_SELECTOR_GENERATOR = bytes4(keccak256("orderEpoch(address,address)"));
+
+    // owner
+    bytes4 constant public OWNER_SELECTOR = 0x8da5cb5b;
+    bytes4 constant public OWNER_SELECTOR_GENERATOR = bytes4(keccak256("owner()"));
+
+    // preSign
+    bytes4 constant public PRE_SIGN_SELECTOR = 0x3683ef8e;
+    bytes4 constant public PRE_SIGN_SELECTOR_GENERATOR = bytes4(keccak256("preSign(bytes32,address,bytes)"));
+
+    // preSigned
+    bytes4 constant public PRE_SIGNED_SELECTOR = 0x82c174d0;
+    bytes4 constant public PRE_SIGNED_SELECTOR_GENERATOR = bytes4(keccak256("preSigned(bytes32,address)"));
+
+    // registerAssetProxy
+    bytes4 constant public REGISTER_ASSET_PROXY_SELECTOR = 0xc585bb93;
+    bytes4 constant public REGISTER_ASSET_PROXY_SELECTOR_GENERATOR = bytes4(keccak256("registerAssetProxy(address)"));
+
+    // setSignatureValidatorApproval
+    bytes4 constant public SET_SIGNATURE_VALIDATOR_APPROVAL_SELECTOR = 0x77fcce68;
+    bytes4 constant public SET_SIGNATURE_VALIDATOR_APPROVAL_SELECTOR_GENERATOR = bytes4(keccak256("setSignatureValidatorApproval(address,bool)"));
+
+    // transactions
+    bytes4 constant public TRANSACTIONS_SELECTOR = 0x642f2eaf;
+    bytes4 constant public TRANSACTIONS_SELECTOR_GENERATOR = bytes4(keccak256("transactions(bytes32)"));
+
+    // transferOwnership
+    bytes4 constant public TRANSFER_OWNERSHIP_SELECTOR = 0xf2fde38b;
+    bytes4 constant public TRANSFER_OWNERSHIP_SELECTOR_GENERATOR = bytes4(keccak256("transferOwnership(address)"));
+}
\ No newline at end of file
diff --git a/contracts/libs/package.json b/contracts/libs/package.json
index fa4b6e523..ce7b97502 100644
--- a/contracts/libs/package.json
+++ b/contracts/libs/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/contracts/multisig/package.json b/contracts/multisig/package.json
index b338f67f7..2d7b4aa05 100644
--- a/contracts/multisig/package.json
+++ b/contracts/multisig/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../packages/abi-gen-templates/contract.handlebars --partials '../../packages/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/contracts/multisig/src/index.ts b/contracts/multisig/src/index.ts
new file mode 100644
index 000000000..d55f08ea2
--- /dev/null
+++ b/contracts/multisig/src/index.ts
@@ -0,0 +1,2 @@
+export * from './artifacts';
+export * from './wrappers';
diff --git a/contracts/protocol/CHANGELOG.json b/contracts/protocol/CHANGELOG.json
index 5c3798a69..be374d892 100644
--- a/contracts/protocol/CHANGELOG.json
+++ b/contracts/protocol/CHANGELOG.json
@@ -1,5 +1,18 @@
 [
     {
+        "version": "2.2.0",
+        "changes": [
+            {
+                "note": "Added LibAddressArray",
+                "pr": 1383
+            },
+            {
+                "note": "Add validation and comments to MultiAssetProxy",
+                "pr": 1455
+            }
+        ]
+    },
+    {
         "timestamp": 1544741676,
         "version": "2.1.59",
         "changes": [
diff --git a/contracts/protocol/contracts/protocol/AssetProxy/MultiAssetProxy.sol b/contracts/protocol/contracts/protocol/AssetProxy/MultiAssetProxy.sol
index 42231e73b..377325384 100644
--- a/contracts/protocol/contracts/protocol/AssetProxy/MultiAssetProxy.sol
+++ b/contracts/protocol/contracts/protocol/AssetProxy/MultiAssetProxy.sol
@@ -33,6 +33,9 @@ contract MultiAssetProxy is
     function ()
         external
     {
+        // NOTE: The below assembly assumes that clients do some input validation and that the input is properly encoded according to the AbiV2 specification.
+        // It is technically possible for inputs with very large lengths and offsets to cause overflows. However, this would make the calldata prohibitively expensive
+        // and we therefore do not check for overflows in these scenarios.
         assembly {
             // The first 4 bytes of calldata holds the function selector
             let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
@@ -145,7 +148,7 @@ contract MultiAssetProxy is
                 let nestedAssetDataLen := calldataload(sub(nestedAssetDataContentsStart, 32))
 
                 // Revert if number of elements in `amounts` differs from number of elements in `nestedAssetData`
-                if iszero(eq(amountsLen, nestedAssetDataLen)) {
+                if sub(amountsLen, nestedAssetDataLen) {
                     // Revert with `Error("LENGTH_MISMATCH")`
                     mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                     mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
@@ -181,8 +184,11 @@ contract MultiAssetProxy is
                     let amountsElement := calldataload(add(amountsContentsStart, i))
                     let totalAmount := mul(amountsElement, amount)
 
-                    // Revert if multiplication resulted in an overflow
-                    if iszero(eq(div(totalAmount, amount), amountsElement)) {
+                    // Revert if `amount` != 0 and multiplication resulted in an overflow 
+                    if iszero(or(
+                        iszero(amount),
+                        eq(div(totalAmount, amount), amountsElement)
+                    )) {
                         // Revert with `Error("UINT256_OVERFLOW")`
                         mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                         mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
@@ -230,7 +236,7 @@ contract MultiAssetProxy is
 
                     // Only load `assetProxy` if `currentAssetProxyId` does not equal `assetProxyId`
                     // We do not need to check if `currentAssetProxyId` is 0 since `assetProxy` is also initialized to 0
-                    if iszero(eq(currentAssetProxyId, assetProxyId)) {
+                    if sub(currentAssetProxyId, assetProxyId) {
                         // Update `assetProxyId`
                         assetProxyId := currentAssetProxyId
                         // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
diff --git a/contracts/protocol/package.json b/contracts/protocol/package.json
index 838189371..d37a0302a 100644
--- a/contracts/protocol/package.json
+++ b/contracts/protocol/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
@@ -44,7 +45,6 @@
     "homepage": "https://github.com/0xProject/0x-monorepo/contracts/protocol/README.md",
     "devDependencies": {
         "@0x/abi-gen": "^1.0.19",
-        "@0x/contracts-test-utils": "^1.0.2",
         "@0x/dev-utils": "^1.0.21",
         "@0x/sol-compiler": "^1.1.16",
         "@0x/sol-cov": "^2.1.16",
@@ -75,6 +75,7 @@
         "@0x/contracts-interfaces": "^1.0.2",
         "@0x/contracts-libs": "^1.0.2",
         "@0x/contracts-multisig": "^1.0.2",
+        "@0x/contracts-test-utils": "^1.0.2",
         "@0x/contracts-tokens": "^1.0.2",
         "@0x/contracts-utils": "^1.0.2",
         "@0x/order-utils": "^3.0.7",
diff --git a/contracts/protocol/test/asset_proxy/proxies.ts b/contracts/protocol/test/asset_proxy/proxies.ts
index c4bd95905..89c8b390c 100644
--- a/contracts/protocol/test/asset_proxy/proxies.ts
+++ b/contracts/protocol/test/asset_proxy/proxies.ts
@@ -12,6 +12,7 @@ import {
 import {
     artifacts as tokensArtifacts,
     DummyERC20TokenContract,
+    DummyERC20TokenTransferEventArgs,
     DummyERC721ReceiverContract,
     DummyERC721TokenContract,
     DummyMultipleReturnERC20TokenContract,
@@ -22,6 +23,7 @@ import { assetDataUtils } from '@0x/order-utils';
 import { RevertReason } from '@0x/types';
 import { BigNumber } from '@0x/utils';
 import * as chai from 'chai';
+import { LogWithDecodedArgs } from 'ethereum-types';
 import * as _ from 'lodash';
 
 import { ERC20ProxyContract } from '../../generated-wrappers/erc20_proxy';
@@ -738,6 +740,36 @@ describe('Asset Transfer Proxies', () => {
                     erc20Balances[toAddress][erc20TokenA.address].add(totalAmount),
                 );
             });
+            it('should dispatch an ERC20 transfer when input amount is 0', async () => {
+                const inputAmount = constants.ZERO_AMOUNT;
+                const erc20Amount = new BigNumber(10);
+                const erc20AssetData = assetDataUtils.encodeERC20AssetData(erc20TokenA.address);
+                const amounts = [erc20Amount];
+                const nestedAssetData = [erc20AssetData];
+                const assetData = assetDataInterface.MultiAsset.getABIEncodedTransactionData(amounts, nestedAssetData);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    assetData,
+                    fromAddress,
+                    toAddress,
+                    inputAmount,
+                );
+                const erc20Balances = await erc20Wrapper.getBalancesAsync();
+                const logDecoder = new LogDecoder(web3Wrapper, { ...artifacts, ...tokensArtifacts });
+                const tx = await logDecoder.getTxWithDecodedLogsAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: multiAssetProxy.address,
+                        data,
+                        from: authorized,
+                    }),
+                );
+                expect(tx.logs.length).to.be.equal(1);
+                const log = tx.logs[0] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>;
+                const transferEventName = 'Transfer';
+                expect(log.event).to.equal(transferEventName);
+                expect(log.args._value).to.be.bignumber.equal(constants.ZERO_AMOUNT);
+                const newBalances = await erc20Wrapper.getBalancesAsync();
+                expect(newBalances).to.deep.equal(erc20Balances);
+            });
             it('should successfully transfer multiple of the same ERC20 token', async () => {
                 const inputAmount = new BigNumber(1);
                 const erc20Amount1 = new BigNumber(10);
diff --git a/contracts/test-utils/src/constants.ts b/contracts/test-utils/src/constants.ts
index d2c3ab512..f631dc81a 100644
--- a/contracts/test-utils/src/constants.ts
+++ b/contracts/test-utils/src/constants.ts
@@ -29,6 +29,7 @@ export const constants = {
     MAX_TOKEN_TRANSFERFROM_GAS: 80000,
     MAX_TOKEN_APPROVE_GAS: 60000,
     MAX_TRANSFER_FROM_GAS: 150000,
+    MAX_MATCH_ORDERS_GAS: 400000,
     DUMMY_TOKEN_NAME: '',
     DUMMY_TOKEN_SYMBOL: '',
     DUMMY_TOKEN_DECIMALS: new BigNumber(18),
diff --git a/contracts/test-utils/src/types.ts b/contracts/test-utils/src/types.ts
index d738fcd4e..1630eab0d 100644
--- a/contracts/test-utils/src/types.ts
+++ b/contracts/test-utils/src/types.ts
@@ -104,6 +104,7 @@ export enum ContractName {
     Authorizable = 'Authorizable',
     Whitelist = 'Whitelist',
     Forwarder = 'Forwarder',
+    BalanceThresholdFilter = 'BalanceThresholdFilter',
 }
 
 export interface SignedTransaction {
diff --git a/contracts/tokens/package.json b/contracts/tokens/package.json
index 6f8a366dd..79afc4820 100644
--- a/contracts/tokens/package.json
+++ b/contracts/tokens/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/contracts/utils/package.json b/contracts/utils/package.json
index a776bdfbb..cf94af0f6 100644
--- a/contracts/utils/package.json
+++ b/contracts/utils/package.json
@@ -19,7 +19,8 @@
         "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha": "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler --contracts-dir contracts",
+        "compile": "sol-compiler",
+        "watch": "sol-compiler -w",
         "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
         "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
         "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
diff --git a/packages/json-schemas/schemas/order_watcher_web_socket_request_schema.json b/packages/json-schemas/schemas/order_watcher_web_socket_request_schema.json
new file mode 100644
index 000000000..b0c419f94
--- /dev/null
+++ b/packages/json-schemas/schemas/order_watcher_web_socket_request_schema.json
@@ -0,0 +1,52 @@
+{
+    "id": "/orderWatcherWebSocketRequestSchema",
+    "type": "object",
+    "definitions": {
+        "signedOrderParam": {
+            "type": "object",
+            "properties": {
+                "signedOrder": { "$ref": "/signedOrderSchema" }
+            },
+            "required": ["signedOrder"]
+        },
+        "orderHashParam": {
+            "type": "object",
+            "properties": {
+                "orderHash": { "$ref": "/hexSchema" }
+            },
+            "required": ["orderHash"]
+        }
+    },
+    "oneOf": [
+        {
+            "type": "object",
+            "properties": {
+                "id": { "type": "number" },
+                "jsonrpc": { "type": "string" },
+                "method": { "enum": ["ADD_ORDER"] },
+                "params": { "$ref": "#/definitions/signedOrderParam" }
+            },
+            "required": ["id", "jsonrpc", "method", "params"]
+        },
+        {
+            "type": "object",
+            "properties": {
+                "id": { "type": "number" },
+                "jsonrpc": { "type": "string" },
+                "method": { "enum": ["REMOVE_ORDER"] },
+                "params": { "$ref": "#/definitions/orderHashParam" }
+            },
+            "required": ["id", "jsonrpc", "method", "params"]
+        },
+        {
+            "type": "object",
+            "properties": {
+                "id": { "type": "number" },
+                "jsonrpc": { "type": "string" },
+                "method": { "enum": ["GET_STATS"] },
+                "params": {}
+            },
+            "required": ["id", "jsonrpc", "method"]
+        }
+    ] 
+}
\ No newline at end of file
diff --git a/packages/json-schemas/schemas/order_watcher_web_socket_utf8_message_schema.json b/packages/json-schemas/schemas/order_watcher_web_socket_utf8_message_schema.json
new file mode 100644
index 000000000..154d6d754
--- /dev/null
+++ b/packages/json-schemas/schemas/order_watcher_web_socket_utf8_message_schema.json
@@ -0,0 +1,10 @@
+{
+    "id": "/orderWatcherWebSocketUtf8MessageSchema",
+    "properties": {
+        "utf8Data": { "type": "string" }
+    },
+    "required": [
+        "utf8Data"
+    ],
+    "type": "object"
+}
diff --git a/packages/json-schemas/src/schemas.ts b/packages/json-schemas/src/schemas.ts
index 21a6f424c..050f4e625 100644
--- a/packages/json-schemas/src/schemas.ts
+++ b/packages/json-schemas/src/schemas.ts
@@ -16,6 +16,8 @@ import * as orderFillOrKillRequestsSchema from '../schemas/order_fill_or_kill_re
 import * as orderFillRequestsSchema from '../schemas/order_fill_requests_schema.json';
 import * as orderHashSchema from '../schemas/order_hash_schema.json';
 import * as orderSchema from '../schemas/order_schema.json';
+import * as orderWatcherWebSocketRequestSchema from '../schemas/order_watcher_web_socket_request_schema.json';
+import * as orderWatcherWebSocketUtf8MessageSchema from '../schemas/order_watcher_web_socket_utf8_message_schema.json';
 import * as orderBookRequestSchema from '../schemas/orderbook_request_schema.json';
 import * as ordersRequestOptsSchema from '../schemas/orders_request_opts_schema.json';
 import * as ordersSchema from '../schemas/orders_schema.json';
@@ -66,6 +68,8 @@ export const schemas = {
     jsNumber,
     requestOptsSchema,
     pagedRequestOptsSchema,
+    orderWatcherWebSocketRequestSchema,
+    orderWatcherWebSocketUtf8MessageSchema,
     ordersRequestOptsSchema,
     orderBookRequestSchema,
     orderConfigRequestSchema,
diff --git a/packages/json-schemas/tsconfig.json b/packages/json-schemas/tsconfig.json
index a79d54385..ec573290c 100644
--- a/packages/json-schemas/tsconfig.json
+++ b/packages/json-schemas/tsconfig.json
@@ -23,6 +23,8 @@
         "./schemas/order_schema.json",
         "./schemas/signed_order_schema.json",
         "./schemas/orders_schema.json",
+        "./schemas/order_watcher_web_socket_request_schema.json",
+        "./schemas/order_watcher_web_socket_utf8_message_schema.json",
         "./schemas/paginated_collection_schema.json",
         "./schemas/relayer_api_asset_data_pairs_response_schema.json",
         "./schemas/relayer_api_asset_data_pairs_schema.json",
diff --git a/packages/order-watcher/CHANGELOG.json b/packages/order-watcher/CHANGELOG.json
index c1fd8d4a9..304dc45fd 100644
--- a/packages/order-watcher/CHANGELOG.json
+++ b/packages/order-watcher/CHANGELOG.json
@@ -1,5 +1,15 @@
 [
     {
+        "version": "2.3.0",
+        "changes": [
+            {
+                "note":
+                    "Added a WebSocket interface to OrderWatcher so that it can be used by a client written in any language",
+                "pr": 1427
+            }
+        ]
+    },
+    {
         "version": "2.2.8",
         "changes": [
             {
diff --git a/packages/order-watcher/README.md b/packages/order-watcher/README.md
index c0b99b272..385fe4715 100644
--- a/packages/order-watcher/README.md
+++ b/packages/order-watcher/README.md
@@ -4,6 +4,9 @@ An order watcher daemon that watches for order validity.
 
 #### Read the wiki [article](https://0xproject.com/wiki#0x-OrderWatcher).
 
+OrderWatcher also comes with a WebSocket server to provide language-agnostic access
+to order watching functionality. We used the [WebSocket Client and Server Implementation for Node](https://www.npmjs.com/package/websocket). The server sends and receives messages that conform to the [JSON RPC specifications](https://www.jsonrpc.org/specification).
+
 ## Installation
 
 **Install**
@@ -26,6 +29,91 @@ If your project is in [TypeScript](https://www.typescriptlang.org/), add the fol
 }
 ```
 
+## Using the WebSocket Server
+
+**Setup**
+
+**Environmental Variables**
+Several environmental variables can be set to configure the server:
+
+*   `ORDER_WATCHER_HTTP_PORT` specifies the port that the http server will listen on
+    and accept connections from. When this is not set, we default to 8080.
+
+**Requests**
+The server accepts three types of requests: `ADD_ORDER`, `REMOVE_ORDER` and `GET_STATS`. These mirror what the underlying OrderWatcher does. You can read more in the [wiki](https://0xproject.com/wiki#0x-OrderWatcher). Unlike the OrderWatcher, it does not expose any `subscribe` or `unsubscribe` functionality because the WebSocket server keeps a single subscription open for all clients.
+
+The first step for making a request is establishing a connection with the server. In Javascript:
+
+```
+var W3CWebSocket = require('websocket').w3cwebsocket;
+wsClient = new W3CWebSocket('ws://127.0.0.1:8080');
+```
+
+In Python, you could use the [websocket-client library](http://pypi.python.org/pypi/websocket-client/) and run:
+
+```
+from websocket import create_connection
+wsClient = create_connection("ws://127.0.0.1:8080")
+```
+
+With the connection established, you prepare the payload for your request. The payload is a json object with a format established by the [JSON RPC specification](https://www.jsonrpc.org/specification):
+
+*   `id`: All requests require you to specify a numerical `id`. When the server responds to the request, the response will have the same `id` as the one supplied with your request.
+*   `jsonrpc`: This is always the string `'2.0'`.
+*   `method`: This specifies the OrderWatcher method you want to call. I.e., `'ADD_ORDER'`, `'REMOVE_ORDER'` or `'GET_STATS'`.
+*   `params`: These contain the parameters needed by OrderWatcher to execute the method you called. For `ADD_ORDER`, provide `{ signedOrder: <your signedOrder> }`. For `REMOVE_ORDER`, provide `{ orderHash: <your orderHash> }`. For `GET_STATS`, no parameters are needed, so you may leave this empty.
+
+Next, convert the payload to a string and send it through the connection.
+In Javascript:
+
+```
+const addOrderPayload = {
+    id: 1,
+    jsonrpc: '2.0',
+    method: 'ADD_ORDER',
+    params: { signedOrder: <your signedOrder> },
+};
+wsClient.send(JSON.stringify(addOrderPayload));
+```
+
+In Python:
+
+```
+import json
+remove_order_payload = {
+    'id': 1,
+    'jsonrpc': '2.0',
+    'method': 'REMOVE_ORDER',
+    'params': {'orderHash': '0x6edc16bf37fde79f5012088c33784c730e2f103d9ab1caf73060c386ad107b7e'},
+}
+wsClient.send(json.dumps(remove_order_payload));
+```
+
+**Response**
+The server responds to all requests in a similar format. In the data field, you'll find another object containing the following fields:
+
+*   `id`: The id corresponding to the request that the server is responding to. `UPDATE` responses are not based on any requests so the `id` field is omitted`.
+*   `jsonrpc`: Always `'2.0'`.
+*   `method`: The method the server is responding to. Eg. `ADD_ORDER`. When order states change the server may also initiate a response. In this case, method will be listed as `UPDATE`.
+*   `result`: This field varies based on the method. `UPDATE` responses contain the new order state. `GET_STATS` responses contain the current order count. When there are errors, this field is omitted.
+*   `error`: When there is an error executing a request, the [JSON RPC](https://www.jsonrpc.org/specification) error object is listed here. When the server responds successfully, this field is omitted.
+
+In Javascript, the responses can be parsed using the `onmessage` callback:
+
+```
+wsClient.onmessage = (msg) => {
+    const responseData = JSON.parse(msg.data);
+    const method = responseData.method
+};
+```
+
+In Python, `recv` is a lightweight way to receive a response:
+
+```
+result = wsClient.recv()
+method = result.method
+```
+
 ## Contributing
 
 We strongly recommend that the community help us make improvements and determine the future direction of the protocol. To report bugs within this package, please create an issue in this repository.
diff --git a/packages/order-watcher/package.json b/packages/order-watcher/package.json
index 499d4cead..16a46294e 100644
--- a/packages/order-watcher/package.json
+++ b/packages/order-watcher/package.json
@@ -74,7 +74,8 @@
         "ethereum-types": "^1.1.4",
         "ethereumjs-blockstream": "6.0.0",
         "ethers": "~4.0.4",
-        "lodash": "^4.17.5"
+        "lodash": "^4.17.5",
+        "websocket": "^1.0.25"
     },
     "publishConfig": {
         "access": "public"
diff --git a/packages/order-watcher/src/index.ts b/packages/order-watcher/src/index.ts
index 5eeba3e87..e275a0c6a 100644
--- a/packages/order-watcher/src/index.ts
+++ b/packages/order-watcher/src/index.ts
@@ -1,4 +1,5 @@
 export { OrderWatcher } from './order_watcher/order_watcher';
+export { OrderWatcherWebSocketServer } from './order_watcher/order_watcher_web_socket_server';
 export { ExpirationWatcher } from './order_watcher/expiration_watcher';
 
 export {
diff --git a/packages/order-watcher/src/order_watcher/order_watcher_web_socket_server.ts b/packages/order-watcher/src/order_watcher/order_watcher_web_socket_server.ts
new file mode 100644
index 000000000..b75b07603
--- /dev/null
+++ b/packages/order-watcher/src/order_watcher/order_watcher_web_socket_server.ts
@@ -0,0 +1,200 @@
+import { ContractAddresses } from '@0x/contract-addresses';
+import { schemas } from '@0x/json-schemas';
+import { OrderStateInvalid, OrderStateValid, SignedOrder } from '@0x/types';
+import { BigNumber, logUtils } from '@0x/utils';
+import { Provider } from 'ethereum-types';
+import * as http from 'http';
+import * as WebSocket from 'websocket';
+
+import { GetStatsResult, OrderWatcherConfig, OrderWatcherMethod, WebSocketRequest, WebSocketResponse } from '../types';
+import { assert } from '../utils/assert';
+
+import { OrderWatcher } from './order_watcher';
+
+const DEFAULT_HTTP_PORT = 8080;
+const JSON_RPC_VERSION = '2.0';
+
+// Wraps the OrderWatcher functionality in a WebSocket server. Motivations:
+// 1) Users can watch orders via non-typescript programs.
+// 2) Better encapsulation so that users can work
+export class OrderWatcherWebSocketServer {
+    private readonly _orderWatcher: OrderWatcher;
+    private readonly _httpServer: http.Server;
+    private readonly _connectionStore: Set<WebSocket.connection>;
+    private readonly _wsServer: WebSocket.server;
+    private readonly _isVerbose: boolean;
+    /**
+     *  Recover types lost when the payload is stringified.
+     */
+    private static _parseSignedOrder(rawRequest: any): SignedOrder {
+        const bigNumberFields = [
+            'salt',
+            'makerFee',
+            'takerFee',
+            'makerAssetAmount',
+            'takerAssetAmount',
+            'expirationTimeSeconds',
+        ];
+        for (const field of bigNumberFields) {
+            rawRequest[field] = new BigNumber(rawRequest[field]);
+        }
+        return rawRequest;
+    }
+
+    /**
+     * Instantiate a new WebSocket server which provides OrderWatcher functionality
+     *  @param provider Web3 provider to use for JSON RPC calls.
+     *  @param networkId NetworkId to watch orders on.
+     *  @param contractAddresses Optional contract addresses. Defaults to known
+     *  addresses based on networkId.
+     *  @param orderWatcherConfig OrderWatcher configurations. isVerbose sets the verbosity for the WebSocket server aswell.
+     *  @param isVerbose Whether to enable verbose logging. Defaults to true.
+     */
+    constructor(
+        provider: Provider,
+        networkId: number,
+        contractAddresses?: ContractAddresses,
+        orderWatcherConfig?: Partial<OrderWatcherConfig>,
+    ) {
+        this._isVerbose =
+            orderWatcherConfig !== undefined && orderWatcherConfig.isVerbose !== undefined
+                ? orderWatcherConfig.isVerbose
+                : true;
+        this._orderWatcher = new OrderWatcher(provider, networkId, contractAddresses, orderWatcherConfig);
+        this._connectionStore = new Set();
+        this._httpServer = http.createServer();
+        this._wsServer = new WebSocket.server({
+            httpServer: this._httpServer,
+            // Avoid setting autoAcceptConnections to true as it defeats all
+            // standard cross-origin protection facilities built into the protocol
+            // and the browser.
+            // Source: https://www.npmjs.com/package/websocket#server-example
+            // Also ensures that a request event is emitted by
+            // the server whenever a new WebSocket request is made.
+            autoAcceptConnections: false,
+        });
+
+        this._wsServer.on('request', async (request: any) => {
+            // Designed for usage pattern where client and server are run on the same
+            // machine by the same user. As such, no security checks are in place.
+            const connection: WebSocket.connection = request.accept(null, request.origin);
+            this._log(`${new Date()} [Server] Accepted connection from origin ${request.origin}.`);
+            connection.on('message', this._onMessageCallbackAsync.bind(this, connection));
+            connection.on('close', this._onCloseCallback.bind(this, connection));
+            this._connectionStore.add(connection);
+        });
+    }
+
+    /**
+     * Activates the WebSocket server by subscribing to the OrderWatcher and
+     * starting the WebSocket's HTTP server
+     */
+    public start(): void {
+        // Have the WebSocket server subscribe to the OrderWatcher to receive updates.
+        // These updates are then broadcast to clients in the _connectionStore.
+        this._orderWatcher.subscribe(this._broadcastCallback.bind(this));
+
+        const port = process.env.ORDER_WATCHER_HTTP_PORT || DEFAULT_HTTP_PORT;
+        this._httpServer.listen(port, () => {
+            this._log(`${new Date()} [Server] Listening on port ${port}`);
+        });
+    }
+
+    /**
+     * Deactivates the WebSocket server by stopping the HTTP server from accepting
+     * new connections and unsubscribing from the OrderWatcher
+     */
+    public stop(): void {
+        this._httpServer.close();
+        this._orderWatcher.unsubscribe();
+    }
+
+    private _log(...args: any[]): void {
+        if (this._isVerbose) {
+            logUtils.log(...args);
+        }
+    }
+
+    private async _onMessageCallbackAsync(connection: WebSocket.connection, message: any): Promise<void> {
+        let response: WebSocketResponse;
+        let id: number | null = null;
+        try {
+            assert.doesConformToSchema('message', message, schemas.orderWatcherWebSocketUtf8MessageSchema);
+            const request: WebSocketRequest = JSON.parse(message.utf8Data);
+            id = request.id;
+            assert.doesConformToSchema('request', request, schemas.orderWatcherWebSocketRequestSchema);
+            assert.isString(request.jsonrpc, JSON_RPC_VERSION);
+            response = {
+                id,
+                jsonrpc: JSON_RPC_VERSION,
+                method: request.method,
+                result: await this._routeRequestAsync(request),
+            };
+        } catch (err) {
+            response = {
+                id,
+                jsonrpc: JSON_RPC_VERSION,
+                method: null,
+                error: err.toString(),
+            };
+        }
+        this._log(`${new Date()} [Server] OrderWatcher output: ${JSON.stringify(response)}`);
+        connection.sendUTF(JSON.stringify(response));
+    }
+
+    private _onCloseCallback(connection: WebSocket.connection): void {
+        this._connectionStore.delete(connection);
+        this._log(`${new Date()} [Server] Client ${connection.remoteAddress} disconnected.`);
+    }
+
+    private async _routeRequestAsync(request: WebSocketRequest): Promise<GetStatsResult | undefined> {
+        this._log(`${new Date()} [Server] Request received: ${request.method}`);
+        switch (request.method) {
+            case OrderWatcherMethod.AddOrder: {
+                const signedOrder: SignedOrder = OrderWatcherWebSocketServer._parseSignedOrder(
+                    request.params.signedOrder,
+                );
+                await this._orderWatcher.addOrderAsync(signedOrder);
+                break;
+            }
+            case OrderWatcherMethod.RemoveOrder: {
+                this._orderWatcher.removeOrder(request.params.orderHash || 'undefined');
+                break;
+            }
+            case OrderWatcherMethod.GetStats: {
+                return this._orderWatcher.getStats();
+            }
+            default:
+                // Should never reach here. Should be caught by JSON schema check.
+                throw new Error(`Unexpected default case hit for request.method`);
+        }
+        return undefined;
+    }
+
+    /**
+     * Broadcasts OrderState changes to ALL connected clients. At the moment,
+     * we do not support clients subscribing to only a subset of orders. As such,
+     * Client B will be notified of changes to an order that Client A added.
+     */
+    private _broadcastCallback(err: Error | null, orderState?: OrderStateValid | OrderStateInvalid | undefined): void {
+        const method = OrderWatcherMethod.Update;
+        const response =
+            err === null
+                ? {
+                      jsonrpc: JSON_RPC_VERSION,
+                      method,
+                      result: orderState,
+                  }
+                : {
+                      jsonrpc: JSON_RPC_VERSION,
+                      method,
+                      error: {
+                          code: -32000,
+                          message: err.message,
+                      },
+                  };
+        this._connectionStore.forEach((connection: WebSocket.connection) => {
+            connection.sendUTF(JSON.stringify(response));
+        });
+    }
+}
diff --git a/packages/order-watcher/src/types.ts b/packages/order-watcher/src/types.ts
index 8078dd971..2b529a939 100644
--- a/packages/order-watcher/src/types.ts
+++ b/packages/order-watcher/src/types.ts
@@ -1,4 +1,4 @@
-import { OrderState } from '@0x/types';
+import { OrderState, SignedOrder } from '@0x/types';
 import { LogEntryEvent } from 'ethereum-types';
 
 export enum OrderWatcherError {
@@ -31,3 +31,67 @@ export enum InternalOrderWatcherError {
     ZrxNotInTokenRegistry = 'ZRX_NOT_IN_TOKEN_REGISTRY',
     WethNotInTokenRegistry = 'WETH_NOT_IN_TOKEN_REGISTRY',
 }
+
+export enum OrderWatcherMethod {
+    // Methods initiated by the user.
+    GetStats = 'GET_STATS',
+    AddOrder = 'ADD_ORDER',
+    RemoveOrder = 'REMOVE_ORDER',
+    // These are spontaneous; they are primarily orderstate changes.
+    Update = 'UPDATE',
+    // `subscribe` and `unsubscribe` are methods of OrderWatcher, but we don't
+    // need to expose them to the WebSocket server user because the user implicitly
+    // subscribes and unsubscribes by connecting and disconnecting from the server.
+}
+
+// Users have to create a json object of this format and attach it to
+// the data field of their WebSocket message to interact with the server.
+export type WebSocketRequest = AddOrderRequest | RemoveOrderRequest | GetStatsRequest;
+
+export interface AddOrderRequest {
+    id: number;
+    jsonrpc: string;
+    method: OrderWatcherMethod.AddOrder;
+    params: { signedOrder: SignedOrder };
+}
+
+export interface RemoveOrderRequest {
+    id: number;
+    jsonrpc: string;
+    method: OrderWatcherMethod.RemoveOrder;
+    params: { orderHash: string };
+}
+
+export interface GetStatsRequest {
+    id: number;
+    jsonrpc: string;
+    method: OrderWatcherMethod.GetStats;
+}
+
+// Users should expect a json object of this format in the data field
+// of the WebSocket messages that the server sends out.
+export type WebSocketResponse = SuccessfulWebSocketResponse | ErrorWebSocketResponse;
+
+export interface SuccessfulWebSocketResponse {
+    id: number;
+    jsonrpc: string;
+    method: OrderWatcherMethod;
+    result: OrderState | GetStatsResult | undefined; // result is undefined for ADD_ORDER and REMOVE_ORDER
+}
+
+export interface ErrorWebSocketResponse {
+    id: number | null;
+    jsonrpc: string;
+    method: null;
+    error: JSONRPCError;
+}
+
+export interface JSONRPCError {
+    code: number;
+    message: string;
+    data?: string | object;
+}
+
+export interface GetStatsResult {
+    orderCount: number;
+}
diff --git a/packages/order-watcher/test/order_watcher_web_socket_server_test.ts b/packages/order-watcher/test/order_watcher_web_socket_server_test.ts
new file mode 100644
index 000000000..578e0de61
--- /dev/null
+++ b/packages/order-watcher/test/order_watcher_web_socket_server_test.ts
@@ -0,0 +1,308 @@
+import { ContractWrappers } from '@0x/contract-wrappers';
+import { tokenUtils } from '@0x/contract-wrappers/lib/test/utils/token_utils';
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import { FillScenarios } from '@0x/fill-scenarios';
+import { assetDataUtils, orderHashUtils } from '@0x/order-utils';
+import { ExchangeContractErrs, OrderStateInvalid, OrderStateValid, SignedOrder } from '@0x/types';
+import { BigNumber, logUtils } from '@0x/utils';
+import { Web3Wrapper } from '@0x/web3-wrapper';
+import * as chai from 'chai';
+import 'mocha';
+import * as WebSocket from 'websocket';
+
+import { OrderWatcherWebSocketServer } from '../src/order_watcher/order_watcher_web_socket_server';
+import { AddOrderRequest, OrderWatcherMethod, RemoveOrderRequest } from '../src/types';
+
+import { chaiSetup } from './utils/chai_setup';
+import { constants } from './utils/constants';
+import { migrateOnceAsync } from './utils/migrate';
+import { provider, web3Wrapper } from './utils/web3_wrapper';
+
+chaiSetup.configure();
+const expect = chai.expect;
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+
+interface WsMessage {
+    data: string;
+}
+
+describe.only('OrderWatcherWebSocketServer', async () => {
+    let contractWrappers: ContractWrappers;
+    let wsServer: OrderWatcherWebSocketServer;
+    let wsClient: WebSocket.w3cwebsocket;
+    let wsClientTwo: WebSocket.w3cwebsocket;
+    let fillScenarios: FillScenarios;
+    let userAddresses: string[];
+    let makerAssetData: string;
+    let takerAssetData: string;
+    let makerTokenAddress: string;
+    let takerTokenAddress: string;
+    let makerAddress: string;
+    let takerAddress: string;
+    let zrxTokenAddress: string;
+    let signedOrder: SignedOrder;
+    let orderHash: string;
+    let addOrderPayload: AddOrderRequest;
+    let removeOrderPayload: RemoveOrderRequest;
+    const decimals = constants.ZRX_DECIMALS;
+    const fillableAmount = Web3Wrapper.toBaseUnitAmount(new BigNumber(5), decimals);
+
+    before(async () => {
+        // Set up constants
+        const contractAddresses = await migrateOnceAsync();
+        await blockchainLifecycle.startAsync();
+        const networkId = constants.TESTRPC_NETWORK_ID;
+        const config = {
+            networkId,
+            contractAddresses,
+        };
+        contractWrappers = new ContractWrappers(provider, config);
+        userAddresses = await web3Wrapper.getAvailableAddressesAsync();
+        zrxTokenAddress = contractAddresses.zrxToken;
+        [makerAddress, takerAddress] = userAddresses;
+        [makerTokenAddress, takerTokenAddress] = tokenUtils.getDummyERC20TokenAddresses();
+        [makerAssetData, takerAssetData] = [
+            assetDataUtils.encodeERC20AssetData(makerTokenAddress),
+            assetDataUtils.encodeERC20AssetData(takerTokenAddress),
+        ];
+        fillScenarios = new FillScenarios(
+            provider,
+            userAddresses,
+            zrxTokenAddress,
+            contractAddresses.exchange,
+            contractAddresses.erc20Proxy,
+            contractAddresses.erc721Proxy,
+        );
+        signedOrder = await fillScenarios.createFillableSignedOrderAsync(
+            makerAssetData,
+            takerAssetData,
+            makerAddress,
+            takerAddress,
+            fillableAmount,
+        );
+        orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+        addOrderPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: OrderWatcherMethod.AddOrder,
+            params: { signedOrder },
+        };
+        removeOrderPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: OrderWatcherMethod.RemoveOrder,
+            params: { orderHash },
+        };
+
+        // Prepare OrderWatcher WebSocket server
+        const orderWatcherConfig = {
+            isVerbose: true,
+        };
+        wsServer = new OrderWatcherWebSocketServer(provider, networkId, contractAddresses, orderWatcherConfig);
+    });
+    after(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    beforeEach(async () => {
+        wsServer.start();
+        await blockchainLifecycle.startAsync();
+        wsClient = new WebSocket.w3cwebsocket('ws://127.0.0.1:8080/');
+        logUtils.log(`${new Date()} [Client] Connected.`);
+    });
+    afterEach(async () => {
+        wsClient.close();
+        await blockchainLifecycle.revertAsync();
+        wsServer.stop();
+        logUtils.log(`${new Date()} [Client] Closed.`);
+    });
+
+    it('responds to getStats requests correctly', (done: any) => {
+        const payload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: 'GET_STATS',
+        };
+        wsClient.onopen = () => wsClient.send(JSON.stringify(payload));
+        wsClient.onmessage = (msg: any) => {
+            const responseData = JSON.parse(msg.data);
+            expect(responseData.id).to.be.eq(1);
+            expect(responseData.jsonrpc).to.be.eq('2.0');
+            expect(responseData.method).to.be.eq('GET_STATS');
+            expect(responseData.result.orderCount).to.be.eq(0);
+            done();
+        };
+    });
+
+    it('throws an error when an invalid method is attempted', async () => {
+        const invalidMethodPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: 'BAD_METHOD',
+        };
+        wsClient.onopen = () => wsClient.send(JSON.stringify(invalidMethodPayload));
+        const errorMsg = await onMessageAsync(wsClient, null);
+        const errorData = JSON.parse(errorMsg.data);
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.id).to.be.null;
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.method).to.be.null;
+        expect(errorData.jsonrpc).to.be.eq('2.0');
+        expect(errorData.error).to.match(/^Error: Expected request to conform to schema/);
+    });
+
+    it('throws an error when jsonrpc field missing from request', async () => {
+        const noJsonRpcPayload = {
+            id: 1,
+            method: 'GET_STATS',
+        };
+        wsClient.onopen = () => wsClient.send(JSON.stringify(noJsonRpcPayload));
+        const errorMsg = await onMessageAsync(wsClient, null);
+        const errorData = JSON.parse(errorMsg.data);
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.method).to.be.null;
+        expect(errorData.jsonrpc).to.be.eq('2.0');
+        expect(errorData.error).to.match(/^Error: Expected request to conform to schema/);
+    });
+
+    it('throws an error when we try to add an order without a signedOrder', async () => {
+        const noSignedOrderAddOrderPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: 'ADD_ORDER',
+            orderHash: '0x7337e2f2a9aa2ed6afe26edc2df7ad79c3ffa9cf9b81a964f707ea63f5272355',
+        };
+        wsClient.onopen = () => wsClient.send(JSON.stringify(noSignedOrderAddOrderPayload));
+        const errorMsg = await onMessageAsync(wsClient, null);
+        const errorData = JSON.parse(errorMsg.data);
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.id).to.be.null;
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.method).to.be.null;
+        expect(errorData.jsonrpc).to.be.eq('2.0');
+        expect(errorData.error).to.match(/^Error: Expected request to conform to schema/);
+    });
+
+    it('throws an error when we try to add a bad signedOrder', async () => {
+        const invalidAddOrderPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: 'ADD_ORDER',
+            signedOrder: {
+                makerAddress: '0x0',
+            },
+        };
+        wsClient.onopen = () => wsClient.send(JSON.stringify(invalidAddOrderPayload));
+        const errorMsg = await onMessageAsync(wsClient, null);
+        const errorData = JSON.parse(errorMsg.data);
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.id).to.be.null;
+        // tslint:disable-next-line:no-unused-expression
+        expect(errorData.method).to.be.null;
+        expect(errorData.error).to.match(/^Error: Expected request to conform to schema/);
+    });
+
+    it('executes addOrder and removeOrder requests correctly', async () => {
+        wsClient.onopen = () => wsClient.send(JSON.stringify(addOrderPayload));
+        const addOrderMsg = await onMessageAsync(wsClient, OrderWatcherMethod.AddOrder);
+        const addOrderData = JSON.parse(addOrderMsg.data);
+        expect(addOrderData.method).to.be.eq('ADD_ORDER');
+        expect((wsServer as any)._orderWatcher._orderByOrderHash).to.deep.include({
+            [orderHash]: signedOrder,
+        });
+
+        const clientOnMessagePromise = onMessageAsync(wsClient, OrderWatcherMethod.RemoveOrder);
+        wsClient.send(JSON.stringify(removeOrderPayload));
+        const removeOrderMsg = await clientOnMessagePromise;
+        const removeOrderData = JSON.parse(removeOrderMsg.data);
+        expect(removeOrderData.method).to.be.eq('REMOVE_ORDER');
+        expect((wsServer as any)._orderWatcher._orderByOrderHash).to.not.deep.include({
+            [orderHash]: signedOrder,
+        });
+    });
+
+    it('broadcasts orderStateInvalid message when makerAddress allowance set to 0 for watched order', async () => {
+        // Add the regular order
+        wsClient.onopen = () => wsClient.send(JSON.stringify(addOrderPayload));
+
+        // We register the onMessage callback before calling `setProxyAllowanceAsync` which we
+        // expect will cause a message to be emitted. We do now "await" here, since we want to
+        // check for messages _after_ calling `setProxyAllowanceAsync`
+        const clientOnMessagePromise = onMessageAsync(wsClient, OrderWatcherMethod.Update);
+
+        // Set the allowance to 0
+        await contractWrappers.erc20Token.setProxyAllowanceAsync(makerTokenAddress, makerAddress, new BigNumber(0));
+
+        // We now await the `onMessage` promise to check for the message
+        const orderWatcherUpdateMsg = await clientOnMessagePromise;
+        const orderWatcherUpdateData = JSON.parse(orderWatcherUpdateMsg.data);
+        expect(orderWatcherUpdateData.method).to.be.eq('UPDATE');
+        const invalidOrderState = orderWatcherUpdateData.result as OrderStateInvalid;
+        expect(invalidOrderState.isValid).to.be.false();
+        expect(invalidOrderState.orderHash).to.be.eq(orderHash);
+        expect(invalidOrderState.error).to.be.eq(ExchangeContractErrs.InsufficientMakerAllowance);
+    });
+
+    it('broadcasts to multiple clients when an order backing ZRX allowance changes', async () => {
+        // Prepare order
+        const makerFee = Web3Wrapper.toBaseUnitAmount(new BigNumber(2), decimals);
+        const takerFee = Web3Wrapper.toBaseUnitAmount(new BigNumber(0), decimals);
+        const nonZeroMakerFeeSignedOrder = await fillScenarios.createFillableSignedOrderWithFeesAsync(
+            makerAssetData,
+            takerAssetData,
+            makerFee,
+            takerFee,
+            makerAddress,
+            takerAddress,
+            fillableAmount,
+            takerAddress,
+        );
+        const nonZeroMakerFeeOrderPayload = {
+            id: 1,
+            jsonrpc: '2.0',
+            method: 'ADD_ORDER',
+            signedOrder: nonZeroMakerFeeSignedOrder,
+        };
+
+        // Set up a second client and have it add the order
+        wsClientTwo = new WebSocket.w3cwebsocket('ws://127.0.0.1:8080/');
+        logUtils.log(`${new Date()} [Client] Connected.`);
+        wsClientTwo.onopen = () => wsClientTwo.send(JSON.stringify(nonZeroMakerFeeOrderPayload));
+
+        // Setup the onMessage callbacks, but don't await them yet
+        const clientOneOnMessagePromise = onMessageAsync(wsClient, OrderWatcherMethod.Update);
+        const clientTwoOnMessagePromise = onMessageAsync(wsClientTwo, OrderWatcherMethod.Update);
+
+        // Change the allowance
+        await contractWrappers.erc20Token.setProxyAllowanceAsync(zrxTokenAddress, makerAddress, new BigNumber(0));
+
+        // Check that both clients receive the emitted event by awaiting the onMessageAsync promises
+        let updateMsg = await clientOneOnMessagePromise;
+        let updateData = JSON.parse(updateMsg.data);
+        let orderState = updateData.result as OrderStateValid;
+        expect(orderState.isValid).to.be.true();
+        expect(orderState.orderRelevantState.makerFeeProxyAllowance).to.be.eq('0');
+
+        updateMsg = await clientTwoOnMessagePromise;
+        updateData = JSON.parse(updateMsg.data);
+        orderState = updateData.result as OrderStateValid;
+        expect(orderState.isValid).to.be.true();
+        expect(orderState.orderRelevantState.makerFeeProxyAllowance).to.be.eq('0');
+
+        wsClientTwo.close();
+        logUtils.log(`${new Date()} [Client] Closed.`);
+    });
+});
+
+// HACK: createFillableSignedOrderAsync is Promise-based, which forces us
+// to use Promises instead of the done() callbacks for tests.
+// onmessage callback must thus be wrapped as a Promise.
+async function onMessageAsync(client: WebSocket.w3cwebsocket, method: string | null): Promise<WsMessage> {
+    return new Promise<WsMessage>(resolve => {
+        client.onmessage = (msg: WsMessage) => {
+            const data = JSON.parse(msg.data);
+            if (data.method === method) {
+                resolve(msg);
+            }
+        };
+    });
+}
diff --git a/packages/sol-compiler/CHANGELOG.json b/packages/sol-compiler/CHANGELOG.json
index 0a757f519..8548fd73f 100644
--- a/packages/sol-compiler/CHANGELOG.json
+++ b/packages/sol-compiler/CHANGELOG.json
@@ -1,5 +1,18 @@
 [
     {
+        "version": "2.0.0",
+        "changes": [
+            {
+                "note": "Add sol-compiler watch mode with -w flag",
+                "pr": 1461
+            },
+            {
+                "note": "Make error and warning colouring more visually pleasant and consistent with other compilers",
+                "pr": 1461
+            }
+        ]
+    },
+    {
         "version": "1.1.16",
         "changes": [
             {
diff --git a/packages/sol-compiler/package.json b/packages/sol-compiler/package.json
index 0ad620b1f..86167a603 100644
--- a/packages/sol-compiler/package.json
+++ b/packages/sol-compiler/package.json
@@ -44,7 +44,9 @@
     "devDependencies": {
         "@0x/dev-utils": "^1.0.21",
         "@0x/tslint-config": "^2.0.0",
+        "@types/chokidar": "^1.7.5",
         "@types/mkdirp": "^0.5.2",
+        "@types/pluralize": "^0.0.29",
         "@types/require-from-string": "^1.2.0",
         "@types/semver": "^5.5.0",
         "chai": "^4.0.1",
@@ -74,10 +76,12 @@
         "@0x/web3-wrapper": "^3.2.1",
         "@types/yargs": "^11.0.0",
         "chalk": "^2.3.0",
+        "chokidar": "^2.0.4",
         "ethereum-types": "^1.1.4",
         "ethereumjs-util": "^5.1.1",
         "lodash": "^4.17.5",
         "mkdirp": "^0.5.1",
+        "pluralize": "^7.0.0",
         "require-from-string": "^2.0.1",
         "semver": "5.5.0",
         "solc": "^0.4.23",
diff --git a/packages/sol-compiler/src/cli.ts b/packages/sol-compiler/src/cli.ts
index 0a9db6e05..18cc68aaf 100644
--- a/packages/sol-compiler/src/cli.ts
+++ b/packages/sol-compiler/src/cli.ts
@@ -25,6 +25,10 @@ const SEPARATOR = ',';
             type: 'string',
             description: 'comma separated list of contracts to compile',
         })
+        .option('watch', {
+            alias: 'w',
+            default: false,
+        })
         .help().argv;
     const contracts = _.isUndefined(argv.contracts)
         ? undefined
@@ -37,7 +41,11 @@ const SEPARATOR = ',';
         contracts,
     };
     const compiler = new Compiler(opts);
-    await compiler.compileAsync();
+    if (argv.watch) {
+        await compiler.watchAsync();
+    } else {
+        await compiler.compileAsync();
+    }
 })().catch(err => {
     logUtils.log(err);
     process.exit(1);
diff --git a/packages/sol-compiler/src/compiler.ts b/packages/sol-compiler/src/compiler.ts
index 85df8209e..d38ccbf39 100644
--- a/packages/sol-compiler/src/compiler.ts
+++ b/packages/sol-compiler/src/compiler.ts
@@ -6,26 +6,29 @@ import {
     NPMResolver,
     RelativeFSResolver,
     Resolver,
+    SpyResolver,
     URLResolver,
 } from '@0x/sol-resolver';
-import { fetchAsync, logUtils } from '@0x/utils';
-import chalk from 'chalk';
+import { logUtils } from '@0x/utils';
+import * as chokidar from 'chokidar';
 import { CompilerOptions, ContractArtifact, ContractVersionData, StandardOutput } from 'ethereum-types';
-import * as ethUtil from 'ethereumjs-util';
 import * as fs from 'fs';
 import * as _ from 'lodash';
 import * as path from 'path';
-import * as requireFromString from 'require-from-string';
+import * as pluralize from 'pluralize';
 import * as semver from 'semver';
 import solc = require('solc');
 
 import { compilerOptionsSchema } from './schemas/compiler_options_schema';
 import { binPaths } from './solc/bin_paths';
 import {
+    addHexPrefixToContractBytecode,
+    compile,
     createDirIfDoesNotExistAsync,
     getContractArtifactIfExistsAsync,
-    getNormalizedErrMsg,
-    parseDependencies,
+    getSolcAsync,
+    getSourcesWithDependencies,
+    getSourceTreeHash,
     parseSolidityVersionRange,
 } from './utils/compiler';
 import { constants } from './utils/constants';
@@ -35,7 +38,6 @@ import { utils } from './utils/utils';
 type TYPE_ALL_FILES_IDENTIFIER = '*';
 const ALL_CONTRACTS_IDENTIFIER = '*';
 const ALL_FILES_IDENTIFIER = '*';
-const SOLC_BIN_DIR = path.join(__dirname, '..', '..', 'solc_bin');
 const DEFAULT_CONTRACTS_DIR = path.resolve('contracts');
 const DEFAULT_ARTIFACTS_DIR = path.resolve('artifacts');
 // Solc compiler settings cannot be configured from the commandline.
@@ -82,49 +84,6 @@ export class Compiler {
     private readonly _artifactsDir: string;
     private readonly _solcVersionIfExists: string | undefined;
     private readonly _specifiedContracts: string[] | TYPE_ALL_FILES_IDENTIFIER;
-    private static async _getSolcAsync(
-        solcVersion: string,
-    ): Promise<{ solcInstance: solc.SolcInstance; fullSolcVersion: string }> {
-        const fullSolcVersion = binPaths[solcVersion];
-        if (_.isUndefined(fullSolcVersion)) {
-            throw new Error(`${solcVersion} is not a known compiler version`);
-        }
-        const compilerBinFilename = path.join(SOLC_BIN_DIR, fullSolcVersion);
-        let solcjs: string;
-        if (await fsWrapper.doesFileExistAsync(compilerBinFilename)) {
-            solcjs = (await fsWrapper.readFileAsync(compilerBinFilename)).toString();
-        } else {
-            logUtils.warn(`Downloading ${fullSolcVersion}...`);
-            const url = `${constants.BASE_COMPILER_URL}${fullSolcVersion}`;
-            const response = await fetchAsync(url);
-            const SUCCESS_STATUS = 200;
-            if (response.status !== SUCCESS_STATUS) {
-                throw new Error(`Failed to load ${fullSolcVersion}`);
-            }
-            solcjs = await response.text();
-            await fsWrapper.writeFileAsync(compilerBinFilename, solcjs);
-        }
-        if (solcjs.length === 0) {
-            throw new Error('No compiler available');
-        }
-        const solcInstance = solc.setupMethods(requireFromString(solcjs, compilerBinFilename));
-        return { solcInstance, fullSolcVersion };
-    }
-    private static _addHexPrefixToContractBytecode(compiledContract: solc.StandardContractOutput): void {
-        if (!_.isUndefined(compiledContract.evm)) {
-            if (!_.isUndefined(compiledContract.evm.bytecode) && !_.isUndefined(compiledContract.evm.bytecode.object)) {
-                compiledContract.evm.bytecode.object = ethUtil.addHexPrefix(compiledContract.evm.bytecode.object);
-            }
-            if (
-                !_.isUndefined(compiledContract.evm.deployedBytecode) &&
-                !_.isUndefined(compiledContract.evm.deployedBytecode.object)
-            ) {
-                compiledContract.evm.deployedBytecode.object = ethUtil.addHexPrefix(
-                    compiledContract.evm.deployedBytecode.object,
-                );
-            }
-        }
-    }
     /**
      * Instantiates a new instance of the Compiler class.
      * @param opts Optional compiler options
@@ -158,7 +117,7 @@ export class Compiler {
      */
     public async compileAsync(): Promise<void> {
         await createDirIfDoesNotExistAsync(this._artifactsDir);
-        await createDirIfDoesNotExistAsync(SOLC_BIN_DIR);
+        await createDirIfDoesNotExistAsync(constants.SOLC_BIN_DIR);
         await this._compileContractsAsync(this._getContractNamesToCompile(), true);
     }
     /**
@@ -173,6 +132,54 @@ export class Compiler {
         const promisedOutputs = this._compileContractsAsync(this._getContractNamesToCompile(), false);
         return promisedOutputs;
     }
+    public async watchAsync(): Promise<void> {
+        console.clear(); // tslint:disable-line:no-console
+        logUtils.logWithTime('Starting compilation in watch mode...');
+        const MATCH_NOTHING_REGEX = '^$';
+        const IGNORE_DOT_FILES_REGEX = /(^|[\/\\])\../;
+        // Initially we watch nothing. We'll add the paths later.
+        const watcher = chokidar.watch(MATCH_NOTHING_REGEX, { ignored: IGNORE_DOT_FILES_REGEX });
+        const onFileChangedAsync = async () => {
+            watcher.unwatch('*'); // Stop watching
+            try {
+                await this.compileAsync();
+                logUtils.logWithTime('Found 0 errors. Watching for file changes.');
+            } catch (err) {
+                if (err.typeName === 'CompilationError') {
+                    logUtils.logWithTime(
+                        `Found ${err.errorsCount} ${pluralize('error', err.errorsCount)}. Watching for file changes.`,
+                    );
+                } else {
+                    logUtils.logWithTime('Found errors. Watching for file changes.');
+                }
+            }
+
+            const pathsToWatch = this._getPathsToWatch();
+            watcher.add(pathsToWatch);
+        };
+        await onFileChangedAsync();
+        watcher.on('change', (changedFilePath: string) => {
+            console.clear(); // tslint:disable-line:no-console
+            logUtils.logWithTime('File change detected. Starting incremental compilation...');
+            // NOTE: We can't await it here because that's a callback.
+            // Instead we stop watching inside of it and start it again when we're finished.
+            onFileChangedAsync(); // tslint:disable-line no-floating-promises
+        });
+    }
+    private _getPathsToWatch(): string[] {
+        const contractNames = this._getContractNamesToCompile();
+        const spyResolver = new SpyResolver(this._resolver);
+        for (const contractName of contractNames) {
+            const contractSource = spyResolver.resolve(contractName);
+            // NOTE: We ignore the return value here. We don't want to compute the source tree hash.
+            // We just want to call a SpyResolver on each contracts and it's dependencies and
+            // this is a convenient way to reuse the existing code that does that.
+            // We can then get all the relevant paths from the `spyResolver` below.
+            getSourceTreeHash(spyResolver, contractSource.path);
+        }
+        const pathsToWatch = _.uniq(spyResolver.resolvedContractSources.map(cs => cs.absolutePath));
+        return pathsToWatch;
+    }
     private _getContractNamesToCompile(): string[] {
         let contractNamesToCompile;
         if (this._specifiedContracts === ALL_CONTRACTS_IDENTIFIER) {
@@ -201,12 +208,14 @@ export class Compiler {
 
         for (const contractName of contractNames) {
             const contractSource = this._resolver.resolve(contractName);
+            const sourceTreeHashHex = getSourceTreeHash(
+                this._resolver,
+                path.join(this._contractsDir, contractSource.path),
+            ).toString('hex');
             const contractData = {
                 contractName,
                 currentArtifactIfExists: await getContractArtifactIfExistsAsync(this._artifactsDir, contractName),
-                sourceTreeHashHex: `0x${this._getSourceTreeHash(
-                    path.join(this._contractsDir, contractSource.path),
-                ).toString('hex')}`,
+                sourceTreeHashHex: `0x${sourceTreeHashHex}`,
             };
             if (!this._shouldCompile(contractData)) {
                 continue;
@@ -244,9 +253,8 @@ export class Compiler {
                 }) with Solidity v${solcVersion}...`,
             );
 
-            const { solcInstance, fullSolcVersion } = await Compiler._getSolcAsync(solcVersion);
-
-            const compilerOutput = this._compile(solcInstance, input.standardInput);
+            const { solcInstance, fullSolcVersion } = await getSolcAsync(solcVersion);
+            const compilerOutput = compile(this._resolver, solcInstance, input.standardInput);
             compilerOutputs.push(compilerOutput);
 
             for (const contractPath of input.contractsToCompile) {
@@ -259,7 +267,7 @@ export class Compiler {
                     );
                 }
 
-                Compiler._addHexPrefixToContractBytecode(compiledContract);
+                addHexPrefixToContractBytecode(compiledContract);
 
                 if (shouldPersist) {
                     await this._persistCompiledContractAsync(
@@ -298,10 +306,14 @@ export class Compiler {
         const compiledContract = compilerOutput.contracts[contractPath][contractName];
 
         // need to gather sourceCodes for this artifact, but compilerOutput.sources (the list of contract modules)
-        // contains listings for for every contract compiled during the compiler invocation that compiled the contract
+        // contains listings for every contract compiled during the compiler invocation that compiled the contract
         // to be persisted, which could include many that are irrelevant to the contract at hand.  So, gather up only
         // the relevant sources:
-        const { sourceCodes, sources } = this._getSourcesWithDependencies(contractPath, compilerOutput.sources);
+        const { sourceCodes, sources } = getSourcesWithDependencies(
+            this._resolver,
+            contractPath,
+            compilerOutput.sources,
+        );
 
         const contractVersion: ContractVersionData = {
             compilerOutput: compiledContract,
@@ -336,130 +348,4 @@ export class Compiler {
         await fsWrapper.writeFileAsync(currentArtifactPath, artifactString);
         logUtils.warn(`${contractName} artifact saved!`);
     }
-    /**
-     * For the given @param contractPath, populates JSON objects to be used in the ContractVersionData interface's
-     * properties `sources` (source code file names mapped to ID numbers) and `sourceCodes` (source code content of
-     * contracts) for that contract.  The source code pointed to by contractPath is read and parsed directly (via
-     * `this._resolver.resolve().source`), as are its imports, recursively.  The ID numbers for @return `sources` are
-     * taken from the corresponding ID's in @param fullSources, and the content for @return sourceCodes is read from
-     * disk (via the aforementioned `resolver.source`).
-     */
-    private _getSourcesWithDependencies(
-        contractPath: string,
-        fullSources: { [sourceName: string]: { id: number } },
-    ): { sourceCodes: { [sourceName: string]: string }; sources: { [sourceName: string]: { id: number } } } {
-        const sources = { [contractPath]: { id: fullSources[contractPath].id } };
-        const sourceCodes = { [contractPath]: this._resolver.resolve(contractPath).source };
-        this._recursivelyGatherDependencySources(
-            contractPath,
-            sourceCodes[contractPath],
-            fullSources,
-            sources,
-            sourceCodes,
-        );
-        return { sourceCodes, sources };
-    }
-    private _recursivelyGatherDependencySources(
-        contractPath: string,
-        contractSource: string,
-        fullSources: { [sourceName: string]: { id: number } },
-        sourcesToAppendTo: { [sourceName: string]: { id: number } },
-        sourceCodesToAppendTo: { [sourceName: string]: string },
-    ): void {
-        const importStatementMatches = contractSource.match(/\nimport[^;]*;/g);
-        if (importStatementMatches === null) {
-            return;
-        }
-        for (const importStatementMatch of importStatementMatches) {
-            const importPathMatches = importStatementMatch.match(/\"([^\"]*)\"/);
-            if (importPathMatches === null || importPathMatches.length === 0) {
-                continue;
-            }
-
-            let importPath = importPathMatches[1];
-            // HACK(ablrow): We have, e.g.:
-            //
-            //      importPath   = "../../utils/LibBytes/LibBytes.sol"
-            //      contractPath = "2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol"
-            //
-            // Resolver doesn't understand "../" so we want to pass
-            // "2.0.0/utils/LibBytes/LibBytes.sol" to resolver.
-            //
-            // This hack involves using path.resolve. But path.resolve returns
-            // absolute directories by default. We trick it into thinking that
-            // contractPath is a root directory by prepending a '/' and then
-            // removing the '/' the end.
-            //
-            //      path.resolve("/a/b/c", ""../../d/e") === "/a/d/e"
-            //
-            const lastPathSeparatorPos = contractPath.lastIndexOf('/');
-            const contractFolder = lastPathSeparatorPos === -1 ? '' : contractPath.slice(0, lastPathSeparatorPos + 1);
-            if (importPath.startsWith('.')) {
-                /**
-                 * Some imports path are relative ("../Token.sol", "./Wallet.sol")
-                 * while others are absolute ("Token.sol", "@0x/contracts/Wallet.sol")
-                 * And we need to append the base path for relative imports.
-                 */
-                importPath = path.resolve(`/${contractFolder}`, importPath).replace('/', '');
-            }
-
-            if (_.isUndefined(sourcesToAppendTo[importPath])) {
-                sourcesToAppendTo[importPath] = { id: fullSources[importPath].id };
-                sourceCodesToAppendTo[importPath] = this._resolver.resolve(importPath).source;
-
-                this._recursivelyGatherDependencySources(
-                    importPath,
-                    this._resolver.resolve(importPath).source,
-                    fullSources,
-                    sourcesToAppendTo,
-                    sourceCodesToAppendTo,
-                );
-            }
-        }
-    }
-    private _compile(solcInstance: solc.SolcInstance, standardInput: solc.StandardInput): solc.StandardOutput {
-        const compiled: solc.StandardOutput = JSON.parse(
-            solcInstance.compileStandardWrapper(JSON.stringify(standardInput), importPath => {
-                const sourceCodeIfExists = this._resolver.resolve(importPath);
-                return { contents: sourceCodeIfExists.source };
-            }),
-        );
-        if (!_.isUndefined(compiled.errors)) {
-            const SOLIDITY_WARNING = 'warning';
-            const errors = _.filter(compiled.errors, entry => entry.severity !== SOLIDITY_WARNING);
-            const warnings = _.filter(compiled.errors, entry => entry.severity === SOLIDITY_WARNING);
-            if (!_.isEmpty(errors)) {
-                errors.forEach(error => {
-                    const normalizedErrMsg = getNormalizedErrMsg(error.formattedMessage || error.message);
-                    logUtils.warn(chalk.red(normalizedErrMsg));
-                });
-                throw new Error('Compilation errors encountered');
-            } else {
-                warnings.forEach(warning => {
-                    const normalizedWarningMsg = getNormalizedErrMsg(warning.formattedMessage || warning.message);
-                    logUtils.warn(chalk.yellow(normalizedWarningMsg));
-                });
-            }
-        }
-        return compiled;
-    }
-    /**
-     * Gets the source tree hash for a file and its dependencies.
-     * @param fileName Name of contract file.
-     */
-    private _getSourceTreeHash(importPath: string): Buffer {
-        const contractSource = this._resolver.resolve(importPath);
-        const dependencies = parseDependencies(contractSource);
-        const sourceHash = ethUtil.sha3(contractSource.source);
-        if (dependencies.length === 0) {
-            return sourceHash;
-        } else {
-            const dependencySourceTreeHashes = _.map(dependencies, (dependency: string) =>
-                this._getSourceTreeHash(dependency),
-            );
-            const sourceTreeHashesBuffer = Buffer.concat([sourceHash, ...dependencySourceTreeHashes]);
-            const sourceTreeHash = ethUtil.sha3(sourceTreeHashesBuffer);
-            return sourceTreeHash;
-        }
-    }
 }
diff --git a/packages/sol-compiler/src/utils/compiler.ts b/packages/sol-compiler/src/utils/compiler.ts
index cda67a414..db308f2b5 100644
--- a/packages/sol-compiler/src/utils/compiler.ts
+++ b/packages/sol-compiler/src/utils/compiler.ts
@@ -1,10 +1,18 @@
-import { ContractSource } from '@0x/sol-resolver';
-import { logUtils } from '@0x/utils';
+import { ContractSource, Resolver } from '@0x/sol-resolver';
+import { fetchAsync, logUtils } from '@0x/utils';
+import chalk from 'chalk';
 import { ContractArtifact } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
 import * as _ from 'lodash';
 import * as path from 'path';
+import * as requireFromString from 'require-from-string';
+import * as solc from 'solc';
 
+import { binPaths } from '../solc/bin_paths';
+
+import { constants } from './constants';
 import { fsWrapper } from './fs_wrapper';
+import { CompilationError } from './types';
 
 /**
  * Gets contract data on network or returns if an artifact does not exist.
@@ -106,3 +114,208 @@ export function parseDependencies(contractSource: ContractSource): string[] {
     });
     return dependencies;
 }
+
+/**
+ * Compiles the contracts and prints errors/warnings
+ * @param resolver Resolver
+ * @param solcInstance Instance of a solc compiler
+ * @param standardInput Solidity standard JSON input
+ */
+export function compile(
+    resolver: Resolver,
+    solcInstance: solc.SolcInstance,
+    standardInput: solc.StandardInput,
+): solc.StandardOutput {
+    const standardInputStr = JSON.stringify(standardInput);
+    const standardOutputStr = solcInstance.compileStandardWrapper(standardInputStr, importPath => {
+        const sourceCodeIfExists = resolver.resolve(importPath);
+        return { contents: sourceCodeIfExists.source };
+    });
+    const compiled: solc.StandardOutput = JSON.parse(standardOutputStr);
+    if (!_.isUndefined(compiled.errors)) {
+        printCompilationErrorsAndWarnings(compiled.errors);
+    }
+    return compiled;
+}
+/**
+ * Separates errors from warnings, formats the messages and prints them. Throws if there is any compilation error (not warning).
+ * @param solcErrors The errors field of standard JSON output that contains errors and warnings.
+ */
+function printCompilationErrorsAndWarnings(solcErrors: solc.SolcError[]): void {
+    const SOLIDITY_WARNING = 'warning';
+    const errors = _.filter(solcErrors, entry => entry.severity !== SOLIDITY_WARNING);
+    const warnings = _.filter(solcErrors, entry => entry.severity === SOLIDITY_WARNING);
+    if (!_.isEmpty(errors)) {
+        errors.forEach(error => {
+            const normalizedErrMsg = getNormalizedErrMsg(error.formattedMessage || error.message);
+            logUtils.log(chalk.red('error'), normalizedErrMsg);
+        });
+        throw new CompilationError(errors.length);
+    } else {
+        warnings.forEach(warning => {
+            const normalizedWarningMsg = getNormalizedErrMsg(warning.formattedMessage || warning.message);
+            logUtils.log(chalk.yellow('warning'), normalizedWarningMsg);
+        });
+    }
+}
+
+/**
+ * Gets the source tree hash for a file and its dependencies.
+ * @param fileName Name of contract file.
+ */
+export function getSourceTreeHash(resolver: Resolver, importPath: string): Buffer {
+    const contractSource = resolver.resolve(importPath);
+    const dependencies = parseDependencies(contractSource);
+    const sourceHash = ethUtil.sha3(contractSource.source);
+    if (dependencies.length === 0) {
+        return sourceHash;
+    } else {
+        const dependencySourceTreeHashes = _.map(dependencies, (dependency: string) =>
+            getSourceTreeHash(resolver, dependency),
+        );
+        const sourceTreeHashesBuffer = Buffer.concat([sourceHash, ...dependencySourceTreeHashes]);
+        const sourceTreeHash = ethUtil.sha3(sourceTreeHashesBuffer);
+        return sourceTreeHash;
+    }
+}
+
+/**
+ * For the given @param contractPath, populates JSON objects to be used in the ContractVersionData interface's
+ * properties `sources` (source code file names mapped to ID numbers) and `sourceCodes` (source code content of
+ * contracts) for that contract.  The source code pointed to by contractPath is read and parsed directly (via
+ * `resolver.resolve().source`), as are its imports, recursively.  The ID numbers for @return `sources` are
+ * taken from the corresponding ID's in @param fullSources, and the content for @return sourceCodes is read from
+ * disk (via the aforementioned `resolver.source`).
+ */
+export function getSourcesWithDependencies(
+    resolver: Resolver,
+    contractPath: string,
+    fullSources: { [sourceName: string]: { id: number } },
+): { sourceCodes: { [sourceName: string]: string }; sources: { [sourceName: string]: { id: number } } } {
+    const sources = { [contractPath]: { id: fullSources[contractPath].id } };
+    const sourceCodes = { [contractPath]: resolver.resolve(contractPath).source };
+    recursivelyGatherDependencySources(
+        resolver,
+        contractPath,
+        sourceCodes[contractPath],
+        fullSources,
+        sources,
+        sourceCodes,
+    );
+    return { sourceCodes, sources };
+}
+
+function recursivelyGatherDependencySources(
+    resolver: Resolver,
+    contractPath: string,
+    contractSource: string,
+    fullSources: { [sourceName: string]: { id: number } },
+    sourcesToAppendTo: { [sourceName: string]: { id: number } },
+    sourceCodesToAppendTo: { [sourceName: string]: string },
+): void {
+    const importStatementMatches = contractSource.match(/\nimport[^;]*;/g);
+    if (importStatementMatches === null) {
+        return;
+    }
+    for (const importStatementMatch of importStatementMatches) {
+        const importPathMatches = importStatementMatch.match(/\"([^\"]*)\"/);
+        if (importPathMatches === null || importPathMatches.length === 0) {
+            continue;
+        }
+
+        let importPath = importPathMatches[1];
+        // HACK(albrow): We have, e.g.:
+        //
+        //      importPath   = "../../utils/LibBytes/LibBytes.sol"
+        //      contractPath = "2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol"
+        //
+        // Resolver doesn't understand "../" so we want to pass
+        // "2.0.0/utils/LibBytes/LibBytes.sol" to resolver.
+        //
+        // This hack involves using path.resolve. But path.resolve returns
+        // absolute directories by default. We trick it into thinking that
+        // contractPath is a root directory by prepending a '/' and then
+        // removing the '/' the end.
+        //
+        //      path.resolve("/a/b/c", ""../../d/e") === "/a/d/e"
+        //
+        const lastPathSeparatorPos = contractPath.lastIndexOf('/');
+        const contractFolder = lastPathSeparatorPos === -1 ? '' : contractPath.slice(0, lastPathSeparatorPos + 1);
+        if (importPath.startsWith('.')) {
+            /**
+             * Some imports path are relative ("../Token.sol", "./Wallet.sol")
+             * while others are absolute ("Token.sol", "@0x/contracts/Wallet.sol")
+             * And we need to append the base path for relative imports.
+             */
+            importPath = path.resolve(`/${contractFolder}`, importPath).replace('/', '');
+        }
+
+        if (_.isUndefined(sourcesToAppendTo[importPath])) {
+            sourcesToAppendTo[importPath] = { id: fullSources[importPath].id };
+            sourceCodesToAppendTo[importPath] = resolver.resolve(importPath).source;
+
+            recursivelyGatherDependencySources(
+                resolver,
+                importPath,
+                resolver.resolve(importPath).source,
+                fullSources,
+                sourcesToAppendTo,
+                sourceCodesToAppendTo,
+            );
+        }
+    }
+}
+
+/**
+ * Gets the solidity compiler instance and full version name. If the compiler is already cached - gets it from FS,
+ * otherwise - fetches it and caches it.
+ * @param solcVersion The compiler version. e.g. 0.5.0
+ */
+export async function getSolcAsync(
+    solcVersion: string,
+): Promise<{ solcInstance: solc.SolcInstance; fullSolcVersion: string }> {
+    const fullSolcVersion = binPaths[solcVersion];
+    if (_.isUndefined(fullSolcVersion)) {
+        throw new Error(`${solcVersion} is not a known compiler version`);
+    }
+    const compilerBinFilename = path.join(constants.SOLC_BIN_DIR, fullSolcVersion);
+    let solcjs: string;
+    if (await fsWrapper.doesFileExistAsync(compilerBinFilename)) {
+        solcjs = (await fsWrapper.readFileAsync(compilerBinFilename)).toString();
+    } else {
+        logUtils.warn(`Downloading ${fullSolcVersion}...`);
+        const url = `${constants.BASE_COMPILER_URL}${fullSolcVersion}`;
+        const response = await fetchAsync(url);
+        const SUCCESS_STATUS = 200;
+        if (response.status !== SUCCESS_STATUS) {
+            throw new Error(`Failed to load ${fullSolcVersion}`);
+        }
+        solcjs = await response.text();
+        await fsWrapper.writeFileAsync(compilerBinFilename, solcjs);
+    }
+    if (solcjs.length === 0) {
+        throw new Error('No compiler available');
+    }
+    const solcInstance = solc.setupMethods(requireFromString(solcjs, compilerBinFilename));
+    return { solcInstance, fullSolcVersion };
+}
+
+/**
+ * Solidity compiler emits the bytecode without a 0x prefix for a hex. This function fixes it if bytecode is present.
+ * @param compiledContract The standard JSON output section for a contract. Geth modified in place.
+ */
+export function addHexPrefixToContractBytecode(compiledContract: solc.StandardContractOutput): void {
+    if (!_.isUndefined(compiledContract.evm)) {
+        if (!_.isUndefined(compiledContract.evm.bytecode) && !_.isUndefined(compiledContract.evm.bytecode.object)) {
+            compiledContract.evm.bytecode.object = ethUtil.addHexPrefix(compiledContract.evm.bytecode.object);
+        }
+        if (
+            !_.isUndefined(compiledContract.evm.deployedBytecode) &&
+            !_.isUndefined(compiledContract.evm.deployedBytecode.object)
+        ) {
+            compiledContract.evm.deployedBytecode.object = ethUtil.addHexPrefix(
+                compiledContract.evm.deployedBytecode.object,
+            );
+        }
+    }
+}
diff --git a/packages/sol-compiler/src/utils/constants.ts b/packages/sol-compiler/src/utils/constants.ts
index df2ddb3b2..433897f8a 100644
--- a/packages/sol-compiler/src/utils/constants.ts
+++ b/packages/sol-compiler/src/utils/constants.ts
@@ -1,5 +1,8 @@
+import * as path from 'path';
+
 export const constants = {
     SOLIDITY_FILE_EXTENSION: '.sol',
     BASE_COMPILER_URL: 'https://ethereum.github.io/solc-bin/bin/',
     LATEST_ARTIFACT_VERSION: '2.0.0',
+    SOLC_BIN_DIR: path.join(__dirname, '..', '..', 'solc_bin'),
 };
diff --git a/packages/sol-compiler/src/utils/types.ts b/packages/sol-compiler/src/utils/types.ts
index b211cfcbc..64328899d 100644
--- a/packages/sol-compiler/src/utils/types.ts
+++ b/packages/sol-compiler/src/utils/types.ts
@@ -29,3 +29,12 @@ export interface Token {
 }
 
 export type DoneCallback = (err?: Error) => void;
+
+export class CompilationError extends Error {
+    public errorsCount: number;
+    public typeName = 'CompilationError';
+    constructor(errorsCount: number) {
+        super('Compilation errors encountered');
+        this.errorsCount = errorsCount;
+    }
+}
diff --git a/packages/sol-compiler/test/compiler_utils_test.ts b/packages/sol-compiler/test/compiler_utils_test.ts
index 4fe7b994e..b8c18110c 100644
--- a/packages/sol-compiler/test/compiler_utils_test.ts
+++ b/packages/sol-compiler/test/compiler_utils_test.ts
@@ -52,7 +52,7 @@ describe('Compiler utils', () => {
             const source = await fsWrapper.readFileAsync(path, {
                 encoding: 'utf8',
             });
-            const dependencies = parseDependencies({ source, path });
+            const dependencies = parseDependencies({ source, path, absolutePath: path });
             const expectedDependencies = [
                 'zeppelin-solidity/contracts/token/ERC20/ERC20.sol',
                 'packages/sol-compiler/lib/test/fixtures/contracts/TokenTransferProxy.sol',
@@ -68,7 +68,7 @@ describe('Compiler utils', () => {
             const source = await fsWrapper.readFileAsync(path, {
                 encoding: 'utf8',
             });
-            expect(parseDependencies({ source, path })).to.be.deep.equal([
+            expect(parseDependencies({ source, path, absolutePath: path })).to.be.deep.equal([
                 'zeppelin-solidity/contracts/ownership/Ownable.sol',
                 'zeppelin-solidity/contracts/token/ERC20/ERC20.sol',
             ]);
@@ -77,7 +77,7 @@ describe('Compiler utils', () => {
         it.skip('correctly parses commented out dependencies', async () => {
             const path = '';
             const source = `// import "./TokenTransferProxy.sol";`;
-            expect(parseDependencies({ path, source })).to.be.deep.equal([]);
+            expect(parseDependencies({ path, source, absolutePath: path })).to.be.deep.equal([]);
         });
     });
 });
diff --git a/packages/sol-resolver/CHANGELOG.json b/packages/sol-resolver/CHANGELOG.json
index 85398e624..74c4d39c5 100644
--- a/packages/sol-resolver/CHANGELOG.json
+++ b/packages/sol-resolver/CHANGELOG.json
@@ -1,5 +1,18 @@
 [
     {
+        "version": "1.2.1",
+        "changes": [
+            {
+                "note": "Add `absolutePath` to `ContractSource` type",
+                "pr": 1461
+            },
+            {
+                "note": "Add `SpyResolver` that records all resolved contracts data",
+                "pr": 1461
+            }
+        ]
+    },
+    {
         "version": "1.1.1",
         "changes": [
             {
diff --git a/packages/sol-resolver/src/index.ts b/packages/sol-resolver/src/index.ts
index a86053259..f55aca070 100644
--- a/packages/sol-resolver/src/index.ts
+++ b/packages/sol-resolver/src/index.ts
@@ -5,5 +5,6 @@ export { NPMResolver } from './resolvers/npm_resolver';
 export { FSResolver } from './resolvers/fs_resolver';
 export { RelativeFSResolver } from './resolvers/relative_fs_resolver';
 export { NameResolver } from './resolvers/name_resolver';
+export { SpyResolver } from './resolvers/spy_resolver';
 export { EnumerableResolver } from './resolvers/enumerable_resolver';
 export { Resolver } from './resolvers/resolver';
diff --git a/packages/sol-resolver/src/resolvers/fs_resolver.ts b/packages/sol-resolver/src/resolvers/fs_resolver.ts
index 63fc3448e..86128023d 100644
--- a/packages/sol-resolver/src/resolvers/fs_resolver.ts
+++ b/packages/sol-resolver/src/resolvers/fs_resolver.ts
@@ -9,10 +9,7 @@ export class FSResolver extends Resolver {
     public resolveIfExists(importPath: string): ContractSource | undefined {
         if (fs.existsSync(importPath) && fs.lstatSync(importPath).isFile()) {
             const fileContent = fs.readFileSync(importPath).toString();
-            return {
-                source: fileContent,
-                path: importPath,
-            };
+            return { source: fileContent, path: importPath, absolutePath: importPath };
         }
         return undefined;
     }
diff --git a/packages/sol-resolver/src/resolvers/name_resolver.ts b/packages/sol-resolver/src/resolvers/name_resolver.ts
index d6ac6a499..aee326fb7 100644
--- a/packages/sol-resolver/src/resolvers/name_resolver.ts
+++ b/packages/sol-resolver/src/resolvers/name_resolver.ts
@@ -20,10 +20,7 @@ export class NameResolver extends EnumerableResolver {
             if (contractName === lookupContractName) {
                 const absoluteContractPath = path.join(this._contractsDir, filePath);
                 const source = fs.readFileSync(absoluteContractPath).toString();
-                contractSource = {
-                    source,
-                    path: filePath,
-                };
+                contractSource = { source, path: filePath, absolutePath: absoluteContractPath };
                 return true;
             }
             return undefined;
@@ -36,10 +33,7 @@ export class NameResolver extends EnumerableResolver {
         const onFile = (filePath: string) => {
             const absoluteContractPath = path.join(this._contractsDir, filePath);
             const source = fs.readFileSync(absoluteContractPath).toString();
-            const contractSource = {
-                source,
-                path: filePath,
-            };
+            const contractSource = { source, path: filePath, absolutePath: absoluteContractPath };
             contractSources.push(contractSource);
         };
         this._traverseContractsDir(this._contractsDir, onFile);
diff --git a/packages/sol-resolver/src/resolvers/npm_resolver.ts b/packages/sol-resolver/src/resolvers/npm_resolver.ts
index eeb2b5493..3c1d09557 100644
--- a/packages/sol-resolver/src/resolvers/npm_resolver.ts
+++ b/packages/sol-resolver/src/resolvers/npm_resolver.ts
@@ -32,10 +32,7 @@ export class NPMResolver extends Resolver {
                 const lookupPath = path.join(currentPath, 'node_modules', packagePath, pathWithinPackage);
                 if (fs.existsSync(lookupPath) && fs.lstatSync(lookupPath).isFile()) {
                     const fileContent = fs.readFileSync(lookupPath).toString();
-                    return {
-                        source: fileContent,
-                        path: lookupPath,
-                    };
+                    return { source: fileContent, path: importPath, absolutePath: lookupPath };
                 }
                 currentPath = path.dirname(currentPath);
             }
diff --git a/packages/sol-resolver/src/resolvers/relative_fs_resolver.ts b/packages/sol-resolver/src/resolvers/relative_fs_resolver.ts
index ed96040d3..cfff145f9 100644
--- a/packages/sol-resolver/src/resolvers/relative_fs_resolver.ts
+++ b/packages/sol-resolver/src/resolvers/relative_fs_resolver.ts
@@ -13,13 +13,10 @@ export class RelativeFSResolver extends Resolver {
     }
     // tslint:disable-next-line:prefer-function-over-method
     public resolveIfExists(importPath: string): ContractSource | undefined {
-        const filePath = path.join(this._contractsDir, importPath);
+        const filePath = path.resolve(path.join(this._contractsDir, importPath));
         if (fs.existsSync(filePath) && !fs.lstatSync(filePath).isDirectory()) {
             const fileContent = fs.readFileSync(filePath).toString();
-            return {
-                source: fileContent,
-                path: importPath,
-            };
+            return { source: fileContent, path: importPath, absolutePath: filePath };
         }
         return undefined;
     }
diff --git a/packages/sol-resolver/src/resolvers/spy_resolver.ts b/packages/sol-resolver/src/resolvers/spy_resolver.ts
new file mode 100644
index 000000000..5582d771a
--- /dev/null
+++ b/packages/sol-resolver/src/resolvers/spy_resolver.ts
@@ -0,0 +1,25 @@
+import * as _ from 'lodash';
+
+import { ContractSource } from '../types';
+
+import { Resolver } from './resolver';
+
+/**
+ * This resolver is a passthrough proxy to any resolver that records all the resolved contracts sources.
+ * You can access them later using the `resolvedContractSources` public field.
+ */
+export class SpyResolver extends Resolver {
+    public resolvedContractSources: ContractSource[] = [];
+    private readonly _resolver: Resolver;
+    constructor(resolver: Resolver) {
+        super();
+        this._resolver = resolver;
+    }
+    public resolveIfExists(importPath: string): ContractSource | undefined {
+        const contractSourceIfExists = this._resolver.resolveIfExists(importPath);
+        if (!_.isUndefined(contractSourceIfExists)) {
+            this.resolvedContractSources.push(contractSourceIfExists);
+        }
+        return contractSourceIfExists;
+    }
+}
diff --git a/packages/sol-resolver/src/resolvers/url_resolver.ts b/packages/sol-resolver/src/resolvers/url_resolver.ts
index 180b0c9f6..ef300e6db 100644
--- a/packages/sol-resolver/src/resolvers/url_resolver.ts
+++ b/packages/sol-resolver/src/resolvers/url_resolver.ts
@@ -11,10 +11,7 @@ export class URLResolver extends Resolver {
         if (importPath.startsWith(FILE_URL_PREXIF)) {
             const filePath = importPath.substr(FILE_URL_PREXIF.length);
             const fileContent = fs.readFileSync(filePath).toString();
-            return {
-                source: fileContent,
-                path: importPath,
-            };
+            return { source: fileContent, path: importPath, absolutePath: filePath };
         }
         return undefined;
     }
diff --git a/packages/sol-resolver/src/types.ts b/packages/sol-resolver/src/types.ts
index 41492622d..b4ba164c8 100644
--- a/packages/sol-resolver/src/types.ts
+++ b/packages/sol-resolver/src/types.ts
@@ -1,6 +1,7 @@
 export interface ContractSource {
     source: string;
     path: string;
+    absolutePath: string;
 }
 
 export interface ContractSources {
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 6b728af71..4470dd501 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -243,6 +243,10 @@ export enum RevertReason {
     AuctionNotStarted = 'AUCTION_NOT_STARTED',
     AuctionInvalidBeginTime = 'INVALID_BEGIN_TIME',
     InvalidAssetData = 'INVALID_ASSET_DATA',
+    // Balance Threshold Filter
+    InvalidOrBlockedExchangeSelector = 'INVALID_OR_BLOCKED_EXCHANGE_SELECTOR',
+    BalanceQueryFailed = 'BALANCE_QUERY_FAILED',
+    AtLeastOneAddressDoesNotMeetBalanceThreshold = 'AT_LEAST_ONE_ADDRESS_DOES_NOT_MEET_BALANCE_THRESHOLD',
 }
 
 export enum StatusCodes {
diff --git a/packages/typescript-typings/tsconfig.json b/packages/typescript-typings/tsconfig.json
index 7f0fe2f7a..8ea3bfb0c 100644
--- a/packages/typescript-typings/tsconfig.json
+++ b/packages/typescript-typings/tsconfig.json
@@ -3,5 +3,6 @@
     "compilerOptions": {
         "outDir": "lib",
         "rootDir": "."
-    }
+    },
+    "include": ["types"]
 }
diff --git a/packages/utils/CHANGELOG.json b/packages/utils/CHANGELOG.json
index fe66d3f31..605151fb6 100644
--- a/packages/utils/CHANGELOG.json
+++ b/packages/utils/CHANGELOG.json
@@ -1,5 +1,14 @@
 [
     {
+        "version": "2.1.0",
+        "changes": [
+            {
+                "note": "Add `logWithTime` to `logUtils`",
+                "pr": 1461
+            }
+        ]
+    },
+    {
         "version": "2.0.8",
         "changes": [
             {
diff --git a/packages/utils/package.json b/packages/utils/package.json
index a25dc9cff..5ffec049a 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -49,6 +49,7 @@
         "@types/node": "*",
         "abortcontroller-polyfill": "^1.1.9",
         "bignumber.js": "~4.1.0",
+        "chalk": "^2.4.1",
         "detect-node": "2.0.3",
         "ethereum-types": "^1.1.4",
         "ethereumjs-util": "^5.1.1",
diff --git a/packages/utils/src/log_utils.ts b/packages/utils/src/log_utils.ts
index 87f8479b5..6d9996c67 100644
--- a/packages/utils/src/log_utils.ts
+++ b/packages/utils/src/log_utils.ts
@@ -1,3 +1,5 @@
+import chalk from 'chalk';
+
 export const logUtils = {
     log(...args: any[]): void {
         console.log(...args); // tslint:disable-line:no-console
@@ -5,4 +7,7 @@ export const logUtils = {
     warn(...args: any[]): void {
         console.warn(...args); // tslint:disable-line:no-console
     },
+    logWithTime(arg: string): void {
+        logUtils.log(`[${chalk.gray(new Date().toLocaleTimeString())}] ${arg}`);
+    },
 };
diff --git a/packages/website/ts/pages/documentation/docs_home.tsx b/packages/website/ts/pages/documentation/docs_home.tsx
index c52d7bd8b..fd3932bfa 100644
--- a/packages/website/ts/pages/documentation/docs_home.tsx
+++ b/packages/website/ts/pages/documentation/docs_home.tsx
@@ -100,6 +100,14 @@ const CATEGORY_TO_PACKAGES: ObjectMap<Package[]> = {
             },
         },
         {
+            description: 'A Python Standard Relayer API client',
+            link: {
+                title: '0x-sra-client.py',
+                to: 'https://pypi.org/project/0x-sra-client/',
+                shouldOpenInNewTab: true,
+            },
+        },
+        {
             description:
                 'An http & websocket client for interacting with relayers that have implemented the [Standard Relayer API](https://github.com/0xProject/standard-relayer-api)',
             link: {
diff --git a/python-packages/sra_client/tox.ini b/python-packages/sra_client/tox.ini
index 3d0be613c..69d59f4ff 100644
--- a/python-packages/sra_client/tox.ini
+++ b/python-packages/sra_client/tox.ini
@@ -8,3 +8,17 @@ deps=-r{toxinidir}/requirements.txt
 commands=
    nosetests \
       []
+
+[testenv:run_tests_against_test_deployment]
+commands =
+    # install dependencies from real PyPI
+    pip install mypy_extensions pytest
+    # install package-under-test from test PyPI
+    pip install --index-url https://test.pypi.org/legacy/ 0x-sra-client
+    pytest test
+
+[testenv:run_tests_against_deployment]
+deps=pytest
+commands =
+    pip install 0x-sra-client
+    pytest test
diff --git a/yarn.lock b/yarn.lock
index f0faee856..0953cbc74 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1299,6 +1299,14 @@
   version "0.22.9"
   resolved "https://registry.npmjs.org/@types/cheerio/-/cheerio-0.22.9.tgz#b5990152604c2ada749b7f88cab3476f21f39d7b"
 
+"@types/chokidar@^1.7.5":
+  version "1.7.5"
+  resolved "https://registry.yarnpkg.com/@types/chokidar/-/chokidar-1.7.5.tgz#1fa78c8803e035bed6d98e6949e514b133b0c9b6"
+  integrity sha512-PDkSRY7KltW3M60hSBlerxI8SFPXsO3AL/aRVsO4Kh9IHRW74Ih75gUuTd/aE4LSSFqypb10UIX3QzOJwBQMGQ==
+  dependencies:
+    "@types/events" "*"
+    "@types/node" "*"
+
 "@types/compare-versions@^3.0.0":
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/@types/compare-versions/-/compare-versions-3.0.0.tgz#4a45dffe0ebbc00d0f2daef8a0e96ffc66cf5955"
@@ -1550,6 +1558,11 @@
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/@types/p-limit/-/p-limit-2.0.0.tgz#c076b7daa9163108a35899ea6a9d927526943ea2"
 
+"@types/pluralize@^0.0.29":
+  version "0.0.29"
+  resolved "https://registry.yarnpkg.com/@types/pluralize/-/pluralize-0.0.29.tgz#6ffa33ed1fc8813c469b859681d09707eb40d03c"
+  integrity sha512-BYOID+l2Aco2nBik+iYS4SZX0Lf20KPILP5RGmM1IgzdwNdTs0eebiFriOPcej1sX9mLnSoiNte5zcFxssgpGA==
+
 "@types/prop-types@*":
   version "15.5.5"
   resolved "https://registry.npmjs.org/@types/prop-types/-/prop-types-15.5.5.tgz#17038dd322c2325f5da650a94d5f9974943625e3"
@@ -4149,6 +4162,26 @@ chokidar@^2.0.0, chokidar@^2.0.2:
   optionalDependencies:
     fsevents "^1.1.2"
 
+chokidar@^2.0.4:
+  version "2.0.4"
+  resolved "https://registry.yarnpkg.com/chokidar/-/chokidar-2.0.4.tgz#356ff4e2b0e8e43e322d18a372460bbcf3accd26"
+  integrity sha512-z9n7yt9rOvIJrMhvDtDictKrkFHeihkNl6uWMmZlmL6tJtX9Cs+87oK+teBx+JIgzvbX3yZHT3eF8vpbDxHJXQ==
+  dependencies:
+    anymatch "^2.0.0"
+    async-each "^1.0.0"
+    braces "^2.3.0"
+    glob-parent "^3.1.0"
+    inherits "^2.0.1"
+    is-binary-path "^1.0.0"
+    is-glob "^4.0.0"
+    lodash.debounce "^4.0.8"
+    normalize-path "^2.1.1"
+    path-is-absolute "^1.0.0"
+    readdirp "^2.0.0"
+    upath "^1.0.5"
+  optionalDependencies:
+    fsevents "^1.2.2"
+
 chownr@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/chownr/-/chownr-1.0.1.tgz#e2a75042a9551908bebd25b8523d5f9769d79181"
@@ -7237,7 +7270,7 @@ fs.realpath@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
 
-fsevents@^1.0.0, fsevents@^1.2.3:
+fsevents@^1.0.0, fsevents@^1.2.2, fsevents@^1.2.3:
   version "1.2.4"
   resolved "https://registry.npmjs.org/fsevents/-/fsevents-1.2.4.tgz#f41dcb1af2582af3692da36fc55cbd8e1041c426"
   dependencies:
@@ -10197,6 +10230,11 @@ lodash.camelcase@^3.0.1:
   dependencies:
     lodash._createcompounder "^3.0.0"
 
+lodash.debounce@^4.0.8:
+  version "4.0.8"
+  resolved "https://registry.yarnpkg.com/lodash.debounce/-/lodash.debounce-4.0.8.tgz#82d79bff30a67c4005ffd5e2515300ad9ca4d7af"
+  integrity sha1-gteb/zCmfEAF/9XiUVMArZyk168=
+
 lodash.deburr@^3.0.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/lodash.deburr/-/lodash.deburr-3.2.0.tgz#6da8f54334a366a7cf4c4c76ef8d80aa1b365ed5"
@@ -12326,6 +12364,7 @@ pkginfo@0.x.x:
 pluralize@^7.0.0:
   version "7.0.0"
   resolved "https://registry.yarnpkg.com/pluralize/-/pluralize-7.0.0.tgz#298b89df8b93b0221dbf421ad2b1b1ea23fc6777"
+  integrity sha512-ARhBOdzS3e41FbkW/XWrTEtukqqLoK5+Z/4UeDaLuSW+39JPeFgs4gCGqsrJHVZX0fUrx//4OF0K1CUGwlIFow==
 
 pn@^1.1.0:
   version "1.1.0"
@@ -16534,6 +16573,11 @@ upath@^1.0.0:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/upath/-/upath-1.0.4.tgz#ee2321ba0a786c50973db043a50b7bcba822361d"
 
+upath@^1.0.5:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/upath/-/upath-1.1.0.tgz#35256597e46a581db4793d0ce47fa9aebfc9fabd"
+  integrity sha512-bzpH/oBhoS/QI/YtbkqCg6VEiPYjSZtrHQM6/QnJS6OL9pKUFLqb3aFh4Scvwm45+7iAgiMkLhSbaZxUqmrprw==
+
 update-notifier@^2.3.0, update-notifier@^2.5.0:
   version "2.5.0"
   resolved "https://registry.yarnpkg.com/update-notifier/-/update-notifier-2.5.0.tgz#d0744593e13f161e406acb1d9408b72cad08aff6"