Merge branch 'development'

* development: (939 commits)
  Add asset-buyer to published packages section in README
  Publish
  Updated CHANGELOGS
  Update BuyQuote interface
  force re-build
  Add website build to instructions
  Revert format and re-add changes
  Build website in parallel with other tests since no other test relies on it being built to run
  Add back sourceMap support for both dev/prod
  Upgrade webpack
  Add missing default options
  Remove unused constants
  Add fee order with a takerFee
  Add additional order factory methods and refactor test to use them
  Add comments about buy quote calculation
  Update CHANGELOG
  Fix linter
  Add additional test for slippage
  Add buy_quote_calculator_test
  Add 0x Instant to bundle analysis
  ...

21 files changed, 962 insertions, 515 deletions

diff --git a/packages/order-utils/src/abstract/abstract_balance_and_proxy_allowance_fetcher.ts b/packages/order-utils/src/abstract/abstract_balance_and_proxy_allowance_fetcher.ts
index b2760d98e..c7f06abad 100644
--- a/packages/order-utils/src/abstract/abstract_balance_and_proxy_allowance_fetcher.ts
+++ b/packages/order-utils/src/abstract/abstract_balance_and_proxy_allowance_fetcher.ts
@@ -1,6 +1,23 @@
 import { BigNumber } from '@0xproject/utils';
 
+/**
+ * An abstract class to be implemented in order to use OrderStateUtils. The class that
+ * implements this interface must be capable of fetching the balance and proxyAllowance
+ * for an Ethereum address and assetData
+ */
 export abstract class AbstractBalanceAndProxyAllowanceFetcher {
+    /**
+     * Get balance of assetData for userAddress
+     * @param assetData AssetData for which to fetch the balance
+     * @param userAddress Ethereum address for which to fetch the balance
+     * @return Balance amount in base units
+     */
     public abstract async getBalanceAsync(assetData: string, userAddress: string): Promise<BigNumber>;
+    /**
+     * Get the 0x asset proxy allowance of assetData for userAddress
+     * @param assetData AssetData for which to fetch the allowance
+     * @param userAddress Ethereum address for which to fetch the allowance
+     * @return Allowance amount in base units
+     */
     public abstract async getProxyAllowanceAsync(assetData: string, userAddress: string): Promise<BigNumber>;
 }
diff --git a/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts b/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
index 865ea4e43..fbc1c4718 100644
--- a/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
+++ b/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
@@ -1,7 +1,22 @@
 import { BigNumber } from '@0xproject/utils';
 
+/**
+ * An abstract class to be implemented in order to use OrderStateUtils. The class that
+ * implements this interface must be capable of fetching the amount filled of an order
+ * and whether it's been cancelled.
+ */
 export abstract class AbstractOrderFilledCancelledFetcher {
+    /**
+     * Get the amount of the order's takerToken amount already filled
+     * @param orderHash OrderHash of order we are interested in
+     * @return FilledTakerAmount
+     */
     public abstract async getFilledTakerAmountAsync(orderHash: string): Promise<BigNumber>;
+    /**
+     * Whether an order is cancelled
+     * @param orderHash OrderHash of order we are interested in
+     * @return Whether or not the order is cancelled
+     */
     public abstract async isOrderCancelledAsync(orderHash: string): Promise<boolean>;
     public abstract getZRXAssetData(): string;
 }
diff --git a/packages/order-utils/src/artifacts.ts b/packages/order-utils/src/artifacts.ts
index 3d2d1e953..735cc2403 100644
--- a/packages/order-utils/src/artifacts.ts
+++ b/packages/order-utils/src/artifacts.ts
@@ -1,4 +1,4 @@
-import { ContractArtifact } from '@0xproject/sol-compiler';
+import { ContractArtifact } from 'ethereum-types';
 
 import * as DummyERC20Token from './artifacts/DummyERC20Token.json';
 import * as ERC20Proxy from './artifacts/ERC20Proxy.json';
diff --git a/packages/order-utils/src/eip712_utils.ts b/packages/order-utils/src/eip712_utils.ts
index 2594e6d6d..b303c93dc 100644
--- a/packages/order-utils/src/eip712_utils.ts
+++ b/packages/order-utils/src/eip712_utils.ts
@@ -18,14 +18,14 @@ const EIP712_DOMAIN_SCHEMA: EIP712Schema = {
     ],
 };
 
-export const EIP712Utils = {
+export const eip712Utils = {
     /**
      * Compiles the EIP712Schema and returns the hash of the schema.
      * @param   schema The EIP712 schema.
      * @return  The hash of the compiled schema
      */
     compileSchema(schema: EIP712Schema): Buffer {
-        const eip712Schema = EIP712Utils._encodeType(schema);
+        const eip712Schema = eip712Utils._encodeType(schema);
         const eip712SchemaHashBuffer = crypto.solSHA3([eip712Schema]);
         return eip712SchemaHashBuffer;
     },
@@ -36,25 +36,47 @@ export const EIP712Utils = {
      * @return  The hash of an EIP712 message with domain separator prefixed
      */
     createEIP712Message(hashStruct: Buffer, contractAddress: string): Buffer {
-        const domainSeparatorHashBuffer = EIP712Utils._getDomainSeparatorHashBuffer(contractAddress);
+        const domainSeparatorHashBuffer = eip712Utils._getDomainSeparatorHashBuffer(contractAddress);
         const messageBuff = crypto.solSHA3([EIP191_PREFIX, domainSeparatorHashBuffer, hashStruct]);
         return messageBuff;
     },
+    /**
+     * Pad an address to 32 bytes
+     * @param address Address to pad
+     * @return padded address
+     */
     pad32Address(address: string): Buffer {
         const addressBuffer = ethUtil.toBuffer(address);
-        const addressPadded = EIP712Utils.pad32Buffer(addressBuffer);
+        const addressPadded = eip712Utils.pad32Buffer(addressBuffer);
         return addressPadded;
     },
+    /**
+     * Pad an buffer to 32 bytes
+     * @param buffer Address to pad
+     * @return padded buffer
+     */
     pad32Buffer(buffer: Buffer): Buffer {
         const bufferPadded = ethUtil.setLengthLeft(buffer, EIP712_VALUE_LENGTH);
         return bufferPadded;
     },
+    /**
+     * Hash together a EIP712 schema with the corresponding data
+     * @param schema EIP712-compliant schema
+     * @param data Data the complies to the schema
+     * @return A buffer containing the SHA256 hash of the schema and encoded data
+     */
+    structHash(schema: EIP712Schema, data: { [key: string]: any }): Buffer {
+        const encodedData = eip712Utils._encodeData(schema, data);
+        const schemaHash = eip712Utils.compileSchema(schema);
+        const hashBuffer = crypto.solSHA3([schemaHash, ...encodedData]);
+        return hashBuffer;
+    },
     _getDomainSeparatorSchemaBuffer(): Buffer {
-        return EIP712Utils.compileSchema(EIP712_DOMAIN_SCHEMA);
+        return eip712Utils.compileSchema(EIP712_DOMAIN_SCHEMA);
     },
     _getDomainSeparatorHashBuffer(exchangeAddress: string): Buffer {
-        const domainSeparatorSchemaBuffer = EIP712Utils._getDomainSeparatorSchemaBuffer();
-        const encodedData = EIP712Utils._encodeData(EIP712_DOMAIN_SCHEMA, {
+        const domainSeparatorSchemaBuffer = eip712Utils._getDomainSeparatorSchemaBuffer();
+        const encodedData = eip712Utils._encodeData(EIP712_DOMAIN_SCHEMA, {
             name: EIP712_DOMAIN_NAME,
             version: EIP712_DOMAIN_VERSION,
             verifyingContract: exchangeAddress,
@@ -77,17 +99,11 @@ export const EIP712Utils = {
             } else if (parameter.type === EIP712Types.Uint256) {
                 encodedValues.push(value);
             } else if (parameter.type === EIP712Types.Address) {
-                encodedValues.push(EIP712Utils.pad32Address(value));
+                encodedValues.push(eip712Utils.pad32Address(value));
             } else {
                 throw new Error(`Unable to encode ${parameter.type}`);
             }
         }
         return encodedValues;
     },
-    structHash(schema: EIP712Schema, data: { [key: string]: any }): Buffer {
-        const encodedData = EIP712Utils._encodeData(schema, data);
-        const schemaHash = EIP712Utils.compileSchema(schema);
-        const hashBuffer = crypto.solSHA3([schemaHash, ...encodedData]);
-        return hashBuffer;
-    },
 };
diff --git a/packages/order-utils/src/exchange_transfer_simulator.ts b/packages/order-utils/src/exchange_transfer_simulator.ts
index c3a4f9c2a..81c849c64 100644
--- a/packages/order-utils/src/exchange_transfer_simulator.ts
+++ b/packages/order-utils/src/exchange_transfer_simulator.ts
@@ -33,6 +33,10 @@ const ERR_MSG_MAPPING = {
     },
 };
 
+/**
+ * An exchange transfer simulator which simulates asset transfers exactly how the
+ * 0x exchange contract would do them.
+ */
 export class ExchangeTransferSimulator {
     private readonly _store: AbstractBalanceAndProxyAllowanceLazyStore;
     private static _throwValidationError(
@@ -43,6 +47,11 @@ export class ExchangeTransferSimulator {
         const errMsg = ERR_MSG_MAPPING[failureReason][tradeSide][transferType];
         throw new Error(errMsg);
     }
+    /**
+     * Instantiate a ExchangeTransferSimulator
+     * @param store A class that implements AbstractBalanceAndProxyAllowanceLazyStore
+     * @return an instance of ExchangeTransferSimulator
+     */
     constructor(store: AbstractBalanceAndProxyAllowanceLazyStore) {
         this._store = store;
     }
diff --git a/packages/order-utils/src/index.ts b/packages/order-utils/src/index.ts
index 681fbc904..1553647c6 100644
--- a/packages/order-utils/src/index.ts
+++ b/packages/order-utils/src/index.ts
@@ -1,27 +1,49 @@
 export { orderHashUtils } from './order_hash';
-export {
-    isValidSignatureAsync,
-    isValidPresignedSignatureAsync,
-    isValidWalletSignatureAsync,
-    isValidValidatorSignatureAsync,
-    isValidECSignature,
-    ecSignOrderHashAsync,
-    addSignedMessagePrefix,
-    parseECSignature,
-} from './signature_utils';
-export { orderFactory } from './order_factory';
-export { constants } from './constants';
-export { crypto } from './crypto';
+export { signatureUtils } from './signature_utils';
 export { generatePseudoRandomSalt } from './salt';
-export { CreateOrderOpts, OrderError, EIP712Parameter, EIP712Schema, EIP712Types } from './types';
+export { assetDataUtils } from './asset_data_utils';
+export { eip712Utils } from './eip712_utils';
+export { marketUtils } from './market_utils';
+export { rateUtils } from './rate_utils';
+export { sortingUtils } from './sorting_utils';
+export { orderParsingUtils } from './parsing_utils';
+
+export { OrderStateUtils } from './order_state_utils';
 export { AbstractBalanceAndProxyAllowanceFetcher } from './abstract/abstract_balance_and_proxy_allowance_fetcher';
+export { AbstractBalanceAndProxyAllowanceLazyStore } from './abstract/abstract_balance_and_proxy_allowance_lazy_store';
 export { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_filled_cancelled_fetcher';
-export { BalanceAndProxyAllowanceLazyStore } from './store/balance_and_proxy_allowance_lazy_store';
-export { OrderFilledCancelledLazyStore } from './store/order_filled_cancelled_lazy_store';
-export { RemainingFillableCalculator } from './remaining_fillable_calculator';
-export { OrderStateUtils } from './order_state_utils';
-export { assetDataUtils } from './asset_data_utils';
-export { EIP712Utils } from './eip712_utils';
+export { AbstractOrderFilledCancelledLazyStore } from './abstract/abstract_order_filled_cancelled_lazy_store';
+
 export { OrderValidationUtils } from './order_validation_utils';
 export { ExchangeTransferSimulator } from './exchange_transfer_simulator';
-export { marketUtils } from './market_utils';
+export { BalanceAndProxyAllowanceLazyStore } from './store/balance_and_proxy_allowance_lazy_store';
+export { OrderFilledCancelledLazyStore } from './store/order_filled_cancelled_lazy_store';
+
+export { Provider, JSONRPCRequestPayload, JSONRPCErrorCallback, JSONRPCResponsePayload } from 'ethereum-types';
+export {
+    SignedOrder,
+    Order,
+    OrderRelevantState,
+    OrderState,
+    ECSignature,
+    ERC20AssetData,
+    ERC721AssetData,
+    AssetProxyId,
+    SignerType,
+    SignatureType,
+    OrderStateValid,
+    OrderStateInvalid,
+    ExchangeContractErrs,
+} from '@0xproject/types';
+export {
+    OrderError,
+    EIP712Parameter,
+    EIP712Schema,
+    EIP712Types,
+    TradeSide,
+    TransferType,
+    FindFeeOrdersThatCoverFeesForTargetOrdersOpts,
+    FindOrdersThatCoverMakerAssetFillAmountOpts,
+    FeeOrdersAndRemainingFeeAmount,
+    OrdersAndRemainingFillAmount,
+} from './types';
diff --git a/packages/order-utils/src/market_utils.ts b/packages/order-utils/src/market_utils.ts
index 681059ddf..ed6af7d85 100644
--- a/packages/order-utils/src/market_utils.ts
+++ b/packages/order-utils/src/market_utils.ts
@@ -1,57 +1,73 @@
 import { schemas } from '@0xproject/json-schemas';
-import { SignedOrder } from '@0xproject/types';
+import { Order } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as _ from 'lodash';
 
 import { assert } from './assert';
 import { constants } from './constants';
+import {
+    FeeOrdersAndRemainingFeeAmount,
+    FindFeeOrdersThatCoverFeesForTargetOrdersOpts,
+    FindOrdersThatCoverMakerAssetFillAmountOpts,
+    OrdersAndRemainingFillAmount,
+} from './types';
 
 export const marketUtils = {
     /**
-     * Takes an array of orders and returns a subset of those orders that has enough makerAssetAmount (taking into account on-chain balances,
-     * allowances, and partial fills) in order to fill the input makerAssetFillAmount plus slippageBufferAmount. Iterates from first order to last.
+     * Takes an array of orders and returns a subset of those orders that has enough makerAssetAmount
+     * in order to fill the input makerAssetFillAmount plus slippageBufferAmount. Iterates from first order to last order.
      * Sort the input by ascending rate in order to get the subset of orders that will cost the least ETH.
-     * @param   signedOrders                        An array of objects that conform to the SignedOrder interface. All orders should specify the same makerAsset.
-     *                                              All orders should specify WETH as the takerAsset.
-     * @param   remainingFillableMakerAssetAmounts  An array of BigNumbers corresponding to the signedOrders parameter.
-     *                                              You can use OrderStateUtils @0xproject/order-utils to perform blockchain lookups
-     *                                              for these values.
-     * @param   makerAssetFillAmount                The amount of makerAsset desired to be filled.
-     * @param   slippageBufferAmount                An additional amount of makerAsset to be covered by the result in case of trade collisions or partial fills.
+     * @param   orders                      An array of objects that extend the Order interface. All orders should specify the same makerAsset.
+     *                                      All orders should specify WETH as the takerAsset.
+     * @param   makerAssetFillAmount        The amount of makerAsset desired to be filled.
+     * @param   opts                        Optional arguments this function accepts.
      * @return  Resulting orders and remaining fill amount that could not be covered by the input.
      */
-    findOrdersThatCoverMakerAssetFillAmount(
-        signedOrders: SignedOrder[],
-        remainingFillableMakerAssetAmounts: BigNumber[],
+    findOrdersThatCoverMakerAssetFillAmount<T extends Order>(
+        orders: T[],
         makerAssetFillAmount: BigNumber,
-        slippageBufferAmount: BigNumber = constants.ZERO_AMOUNT,
-    ): { resultOrders: SignedOrder[]; remainingFillAmount: BigNumber } {
-        assert.doesConformToSchema('signedOrders', signedOrders, schemas.signedOrdersSchema);
+        opts?: FindOrdersThatCoverMakerAssetFillAmountOpts,
+    ): OrdersAndRemainingFillAmount<T> {
+        assert.doesConformToSchema('orders', orders, schemas.ordersSchema);
+        assert.isValidBaseUnitAmount('makerAssetFillAmount', makerAssetFillAmount);
+        // try to get remainingFillableMakerAssetAmounts from opts, if it's not there, use makerAssetAmount values from orders
+        const remainingFillableMakerAssetAmounts = _.get(
+            opts,
+            'remainingFillableMakerAssetAmounts',
+            _.map(orders, order => order.makerAssetAmount),
+        ) as BigNumber[];
         _.forEach(remainingFillableMakerAssetAmounts, (amount, index) =>
             assert.isValidBaseUnitAmount(`remainingFillableMakerAssetAmount[${index}]`, amount),
         );
-        assert.isValidBaseUnitAmount('makerAssetFillAmount', makerAssetFillAmount);
-        assert.isValidBaseUnitAmount('slippageBufferAmount', slippageBufferAmount);
         assert.assert(
-            signedOrders.length === remainingFillableMakerAssetAmounts.length,
-            'Expected signedOrders.length to equal remainingFillableMakerAssetAmounts.length',
+            orders.length === remainingFillableMakerAssetAmounts.length,
+            'Expected orders.length to equal opts.remainingFillableMakerAssetAmounts.length',
         );
+        // try to get slippageBufferAmount from opts, if it's not there, default to 0
+        const slippageBufferAmount = _.get(opts, 'slippageBufferAmount', constants.ZERO_AMOUNT) as BigNumber;
+        assert.isValidBaseUnitAmount('opts.slippageBufferAmount', slippageBufferAmount);
         // calculate total amount of makerAsset needed to be filled
         const totalFillAmount = makerAssetFillAmount.plus(slippageBufferAmount);
-        // iterate through the signedOrders input from left to right until we have enough makerAsset to fill totalFillAmount
+        // iterate through the orders input from left to right until we have enough makerAsset to fill totalFillAmount
         const result = _.reduce(
-            signedOrders,
-            ({ resultOrders, remainingFillAmount }, order, index) => {
+            orders,
+            ({ resultOrders, remainingFillAmount, ordersRemainingFillableMakerAssetAmounts }, order, index) => {
                 if (remainingFillAmount.lessThanOrEqualTo(constants.ZERO_AMOUNT)) {
-                    return { resultOrders, remainingFillAmount: constants.ZERO_AMOUNT };
+                    return {
+                        resultOrders,
+                        remainingFillAmount: constants.ZERO_AMOUNT,
+                        ordersRemainingFillableMakerAssetAmounts,
+                    };
                 } else {
                     const makerAssetAmountAvailable = remainingFillableMakerAssetAmounts[index];
+                    const shouldIncludeOrder = makerAssetAmountAvailable.gt(constants.ZERO_AMOUNT);
                     // if there is no makerAssetAmountAvailable do not append order to resultOrders
                     // if we have exceeded the total amount we want to fill set remainingFillAmount to 0
                     return {
-                        resultOrders: makerAssetAmountAvailable.gt(constants.ZERO_AMOUNT)
-                            ? _.concat(resultOrders, order)
-                            : resultOrders,
+                        resultOrders: shouldIncludeOrder ? _.concat(resultOrders, order) : resultOrders,
+                        ordersRemainingFillableMakerAssetAmounts: shouldIncludeOrder
+                            ? _.concat(ordersRemainingFillableMakerAssetAmounts, makerAssetAmountAvailable)
+                            : ordersRemainingFillableMakerAssetAmounts,
                         remainingFillAmount: BigNumber.max(
                             constants.ZERO_AMOUNT,
                             remainingFillAmount.minus(makerAssetAmountAvailable),
@@ -59,73 +75,86 @@ export const marketUtils = {
                     };
                 }
             },
-            { resultOrders: [] as SignedOrder[], remainingFillAmount: totalFillAmount },
+            {
+                resultOrders: [] as T[],
+                remainingFillAmount: totalFillAmount,
+                ordersRemainingFillableMakerAssetAmounts: [] as BigNumber[],
+            },
         );
         return result;
     },
     /**
-     * Takes an array of orders and an array of feeOrders. Returns a subset of the feeOrders that has enough ZRX (taking into account
-     * on-chain balances, allowances, and partial fills) in order to fill the takerFees required by signedOrders plus a
-     * slippageBufferAmount. Iterates from first feeOrder to last. Sort the feeOrders by ascending rate in order to get the subset of
+     * Takes an array of orders and an array of feeOrders. Returns a subset of the feeOrders that has enough ZRX
+     * in order to fill the takerFees required by orders plus a slippageBufferAmount.
+     * Iterates from first feeOrder to last. Sort the feeOrders by ascending rate in order to get the subset of
      * feeOrders that will cost the least ETH.
-     * @param   signedOrders                        An array of objects that conform to the SignedOrder interface. All orders should specify ZRX as
-     *                                              the makerAsset and WETH as the takerAsset.
-     * @param   remainingFillableMakerAssetAmounts  An array of BigNumbers corresponding to the signedOrders parameter.
-     *                                              You can use OrderStateUtils @0xproject/order-utils to perform blockchain lookups
-     *                                              for these values.
-     * @param   signedFeeOrders                     An array of objects that conform to the SignedOrder interface. All orders should specify ZRX as
-     *                                              the makerAsset and WETH as the takerAsset.
-     * @param   remainingFillableFeeAmounts         An array of BigNumbers corresponding to the signedFeeOrders parameter.
-     *                                              You can use OrderStateUtils @0xproject/order-utils to perform blockchain lookups
-     *                                              for these values.
-     * @param   slippageBufferAmount                An additional amount of fee to be covered by the result in case of trade collisions or partial fills.
+     * @param   orders      An array of objects that extend the Order interface. All orders should specify ZRX as
+     *                      the makerAsset and WETH as the takerAsset.
+     * @param   feeOrders   An array of objects that extend the Order interface. All orders should specify ZRX as
+     *                      the makerAsset and WETH as the takerAsset.
+     * @param   opts        Optional arguments this function accepts.
      * @return  Resulting orders and remaining fee amount that could not be covered by the input.
      */
-    findFeeOrdersThatCoverFeesForTargetOrders(
-        signedOrders: SignedOrder[],
-        remainingFillableMakerAssetAmounts: BigNumber[],
-        signedFeeOrders: SignedOrder[],
-        remainingFillableFeeAmounts: BigNumber[],
-        slippageBufferAmount: BigNumber = constants.ZERO_AMOUNT,
-    ): { resultOrders: SignedOrder[]; remainingFeeAmount: BigNumber } {
-        assert.doesConformToSchema('signedOrders', signedOrders, schemas.signedOrdersSchema);
+    findFeeOrdersThatCoverFeesForTargetOrders<T extends Order>(
+        orders: T[],
+        feeOrders: T[],
+        opts?: FindFeeOrdersThatCoverFeesForTargetOrdersOpts,
+    ): FeeOrdersAndRemainingFeeAmount<T> {
+        assert.doesConformToSchema('orders', orders, schemas.ordersSchema);
+        assert.doesConformToSchema('feeOrders', feeOrders, schemas.ordersSchema);
+        // try to get remainingFillableMakerAssetAmounts from opts, if it's not there, use makerAssetAmount values from orders
+        const remainingFillableMakerAssetAmounts = _.get(
+            opts,
+            'remainingFillableMakerAssetAmounts',
+            _.map(orders, order => order.makerAssetAmount),
+        ) as BigNumber[];
         _.forEach(remainingFillableMakerAssetAmounts, (amount, index) =>
             assert.isValidBaseUnitAmount(`remainingFillableMakerAssetAmount[${index}]`, amount),
         );
-        assert.doesConformToSchema('signedFeeOrders', signedFeeOrders, schemas.signedOrdersSchema);
+        assert.assert(
+            orders.length === remainingFillableMakerAssetAmounts.length,
+            'Expected orders.length to equal opts.remainingFillableMakerAssetAmounts.length',
+        );
+        // try to get remainingFillableFeeAmounts from opts, if it's not there, use makerAssetAmount values from feeOrders
+        const remainingFillableFeeAmounts = _.get(
+            opts,
+            'remainingFillableFeeAmounts',
+            _.map(feeOrders, order => order.makerAssetAmount),
+        ) as BigNumber[];
         _.forEach(remainingFillableFeeAmounts, (amount, index) =>
             assert.isValidBaseUnitAmount(`remainingFillableFeeAmounts[${index}]`, amount),
         );
-        assert.isValidBaseUnitAmount('slippageBufferAmount', slippageBufferAmount);
-        assert.assert(
-            signedOrders.length === remainingFillableMakerAssetAmounts.length,
-            'Expected signedOrders.length to equal remainingFillableMakerAssetAmounts.length',
-        );
         assert.assert(
-            signedOrders.length === remainingFillableMakerAssetAmounts.length,
-            'Expected signedFeeOrders.length to equal remainingFillableFeeAmounts.length',
+            feeOrders.length === remainingFillableFeeAmounts.length,
+            'Expected feeOrders.length to equal opts.remainingFillableFeeAmounts.length',
         );
-        // calculate total amount of ZRX needed to fill signedOrders
+        // try to get slippageBufferAmount from opts, if it's not there, default to 0
+        const slippageBufferAmount = _.get(opts, 'slippageBufferAmount', constants.ZERO_AMOUNT) as BigNumber;
+        assert.isValidBaseUnitAmount('opts.slippageBufferAmount', slippageBufferAmount);
+        // calculate total amount of ZRX needed to fill orders
         const totalFeeAmount = _.reduce(
-            signedOrders,
+            orders,
             (accFees, order, index) => {
                 const makerAssetAmountAvailable = remainingFillableMakerAssetAmounts[index];
                 const feeToFillMakerAssetAmountAvailable = makerAssetAmountAvailable
                     .mul(order.takerFee)
-                    .div(order.makerAssetAmount);
+                    .dividedToIntegerBy(order.makerAssetAmount);
                 return accFees.plus(feeToFillMakerAssetAmountAvailable);
             },
             constants.ZERO_AMOUNT,
         );
-        const { resultOrders, remainingFillAmount } = marketUtils.findOrdersThatCoverMakerAssetFillAmount(
-            signedFeeOrders,
-            remainingFillableFeeAmounts,
-            totalFeeAmount,
+        const {
+            resultOrders,
+            remainingFillAmount,
+            ordersRemainingFillableMakerAssetAmounts,
+        } = marketUtils.findOrdersThatCoverMakerAssetFillAmount(feeOrders, totalFeeAmount, {
+            remainingFillableMakerAssetAmounts: remainingFillableFeeAmounts,
             slippageBufferAmount,
-        );
+        });
         return {
-            resultOrders,
+            resultFeeOrders: resultOrders,
             remainingFeeAmount: remainingFillAmount,
+            feeOrdersRemainingFillableMakerAssetAmounts: ordersRemainingFillableMakerAssetAmounts,
         };
         // TODO: add more orders here to cover rounding
         // https://github.com/0xProject/0x-protocol-specification/blob/master/v2/forwarding-contract-specification.md#over-buying-zrx
diff --git a/packages/order-utils/src/monorepo_scripts/postpublish.ts b/packages/order-utils/src/monorepo_scripts/postpublish.ts
deleted file mode 100644
index dcb99d0f7..000000000
--- a/packages/order-utils/src/monorepo_scripts/postpublish.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-import { postpublishUtils } from '@0xproject/monorepo-scripts';
-
-import * as packageJSON from '../package.json';
-import * as tsConfigJSON from '../tsconfig.json';
-
-const cwd = `${__dirname}/..`;
-// tslint:disable-next-line:no-floating-promises
-postpublishUtils.runAsync(packageJSON, tsConfigJSON, cwd);
diff --git a/packages/order-utils/src/monorepo_scripts/stage_docs.ts b/packages/order-utils/src/monorepo_scripts/stage_docs.ts
deleted file mode 100644
index e732ac8eb..000000000
--- a/packages/order-utils/src/monorepo_scripts/stage_docs.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-import { postpublishUtils } from '@0xproject/monorepo-scripts';
-
-import * as packageJSON from '../package.json';
-import * as tsConfigJSON from '../tsconfig.json';
-
-const cwd = `${__dirname}/..`;
-// tslint:disable-next-line:no-floating-promises
-postpublishUtils.publishDocsToStagingAsync(packageJSON, tsConfigJSON, cwd);
diff --git a/packages/order-utils/src/order_factory.ts b/packages/order-utils/src/order_factory.ts
index 4a6f3924b..b1292903a 100644
--- a/packages/order-utils/src/order_factory.ts
+++ b/packages/order-utils/src/order_factory.ts
@@ -6,10 +6,23 @@ import * as _ from 'lodash';
 import { constants } from './constants';
 import { orderHashUtils } from './order_hash';
 import { generatePseudoRandomSalt } from './salt';
-import { ecSignOrderHashAsync } from './signature_utils';
+import { signatureUtils } from './signature_utils';
 import { CreateOrderOpts } from './types';
-
 export const orderFactory = {
+    createOrderFromPartial(partialOrder: Partial<Order>): Order {
+        const defaultOrder = generateEmptyOrder();
+        return {
+            ...defaultOrder,
+            ...partialOrder,
+        };
+    },
+    createSignedOrderFromPartial(partialSignedOrder: Partial<SignedOrder>): SignedOrder {
+        const defaultOrder = generateEmptySignedOrder();
+        return {
+            ...defaultOrder,
+            ...partialSignedOrder,
+        };
+    },
     createOrder(
         makerAddress: string,
         makerAssetAmount: BigNumber,
@@ -58,12 +71,41 @@ export const orderFactory = {
             createOrderOpts,
         );
         const orderHash = orderHashUtils.getOrderHashHex(order);
-        const signature = await ecSignOrderHashAsync(provider, orderHash, makerAddress, SignerType.Default);
+        const signature = await signatureUtils.ecSignOrderHashAsync(
+            provider,
+            orderHash,
+            makerAddress,
+            SignerType.Default,
+        );
         const signedOrder: SignedOrder = _.assign(order, { signature });
         return signedOrder;
     },
 };
 
+function generateEmptySignedOrder(): SignedOrder {
+    return {
+        ...generateEmptyOrder(),
+        signature: constants.NULL_BYTES,
+    };
+}
+function generateEmptyOrder(): Order {
+    return {
+        senderAddress: constants.NULL_ADDRESS,
+        makerAddress: constants.NULL_ADDRESS,
+        takerAddress: constants.NULL_ADDRESS,
+        makerFee: constants.ZERO_AMOUNT,
+        takerFee: constants.ZERO_AMOUNT,
+        makerAssetAmount: constants.ZERO_AMOUNT,
+        takerAssetAmount: constants.ZERO_AMOUNT,
+        makerAssetData: constants.NULL_BYTES,
+        takerAssetData: constants.NULL_BYTES,
+        salt: generatePseudoRandomSalt(),
+        exchangeAddress: constants.NULL_ADDRESS,
+        feeRecipientAddress: constants.NULL_ADDRESS,
+        expirationTimeSeconds: constants.INFINITE_TIMESTAMP_SEC,
+    };
+}
+
 function generateDefaultCreateOrderOpts(): {
     takerAddress: string;
     senderAddress: string;
diff --git a/packages/order-utils/src/order_hash.ts b/packages/order-utils/src/order_hash.ts
index 54c500653..8e98f8767 100644
--- a/packages/order-utils/src/order_hash.ts
+++ b/packages/order-utils/src/order_hash.ts
@@ -3,7 +3,7 @@ import { Order, SignedOrder } from '@0xproject/types';
 import * as _ from 'lodash';
 
 import { assert } from './assert';
-import { EIP712Utils } from './eip712_utils';
+import { eip712Utils } from './eip712_utils';
 import { EIP712Schema, EIP712Types } from './types';
 
 const INVALID_TAKER_FORMAT = 'instance.takerAddress is not of a type(s) string';
@@ -69,11 +69,11 @@ export const orderHashUtils = {
      * @return  The resulting orderHash from hashing the supplied order as a Buffer
      */
     getOrderHashBuffer(order: SignedOrder | Order): Buffer {
-        const orderParamsHashBuff = EIP712Utils.structHash(EIP712_ORDER_SCHEMA, order);
-        const orderHashBuff = EIP712Utils.createEIP712Message(orderParamsHashBuff, order.exchangeAddress);
+        const orderParamsHashBuff = eip712Utils.structHash(EIP712_ORDER_SCHEMA, order);
+        const orderHashBuff = eip712Utils.createEIP712Message(orderParamsHashBuff, order.exchangeAddress);
         return orderHashBuff;
     },
     _getOrderSchemaBuffer(): Buffer {
-        return EIP712Utils.compileSchema(EIP712_ORDER_SCHEMA);
+        return eip712Utils.compileSchema(EIP712_ORDER_SCHEMA);
     },
 };
diff --git a/packages/order-utils/src/order_state_utils.ts b/packages/order-utils/src/order_state_utils.ts
index 189bf4180..9b21ef6e9 100644
--- a/packages/order-utils/src/order_state_utils.ts
+++ b/packages/order-utils/src/order_state_utils.ts
@@ -11,6 +11,7 @@ import { BigNumber } from '@0xproject/utils';
 import { AbstractBalanceAndProxyAllowanceFetcher } from './abstract/abstract_balance_and_proxy_allowance_fetcher';
 import { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_filled_cancelled_fetcher';
 import { orderHashUtils } from './order_hash';
+import { OrderValidationUtils } from './order_validation_utils';
 import { RemainingFillableCalculator } from './remaining_fillable_calculator';
 import { utils } from './utils';
 
@@ -22,9 +23,16 @@ interface SidedOrderRelevantState {
     traderFeeProxyAllowance: BigNumber;
     filledTakerAssetAmount: BigNumber;
     remainingFillableAssetAmount: BigNumber;
+    isOrderCancelled: boolean;
 }
-
-const ACCEPTABLE_RELATIVE_ROUNDING_ERROR = 0.0001;
+interface OrderValidResult {
+    isValid: true;
+}
+interface OrderInvalidResult {
+    isValid: false;
+    error: ExchangeContractErrs;
+}
+type OrderValidationResult = OrderValidResult | OrderInvalidResult;
 
 export class OrderStateUtils {
     private readonly _balanceAndProxyAllowanceFetcher: AbstractBalanceAndProxyAllowanceFetcher;
@@ -32,65 +40,65 @@ export class OrderStateUtils {
     private static _validateIfOrderIsValid(
         signedOrder: SignedOrder,
         sidedOrderRelevantState: SidedOrderRelevantState,
-    ): void {
+    ): OrderValidationResult {
         const isMakerSide = sidedOrderRelevantState.isMakerSide;
+        if (sidedOrderRelevantState.isOrderCancelled) {
+            return { isValid: false, error: ExchangeContractErrs.OrderCancelled };
+        }
         const availableTakerAssetAmount = signedOrder.takerAssetAmount.minus(
             sidedOrderRelevantState.filledTakerAssetAmount,
         );
         if (availableTakerAssetAmount.eq(0)) {
-            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+            return { isValid: false, error: ExchangeContractErrs.OrderRemainingFillAmountZero };
         }
 
         if (sidedOrderRelevantState.traderBalance.eq(0)) {
-            throw new Error(
-                isMakerSide
-                    ? ExchangeContractErrs.InsufficientMakerBalance
-                    : ExchangeContractErrs.InsufficientTakerBalance,
-            );
+            const error = isMakerSide
+                ? ExchangeContractErrs.InsufficientMakerBalance
+                : ExchangeContractErrs.InsufficientTakerBalance;
+            return { isValid: false, error };
         }
         if (sidedOrderRelevantState.traderProxyAllowance.eq(0)) {
-            throw new Error(
-                isMakerSide
-                    ? ExchangeContractErrs.InsufficientMakerAllowance
-                    : ExchangeContractErrs.InsufficientTakerAllowance,
-            );
+            const error = isMakerSide
+                ? ExchangeContractErrs.InsufficientMakerAllowance
+                : ExchangeContractErrs.InsufficientTakerAllowance;
+            return { isValid: false, error };
         }
         if (!signedOrder.makerFee.eq(0)) {
             if (sidedOrderRelevantState.traderFeeBalance.eq(0)) {
-                throw new Error(
-                    isMakerSide
-                        ? ExchangeContractErrs.InsufficientMakerFeeBalance
-                        : ExchangeContractErrs.InsufficientTakerFeeBalance,
-                );
+                const error = isMakerSide
+                    ? ExchangeContractErrs.InsufficientMakerFeeBalance
+                    : ExchangeContractErrs.InsufficientTakerFeeBalance;
+                return { isValid: false, error };
             }
             if (sidedOrderRelevantState.traderFeeProxyAllowance.eq(0)) {
-                throw new Error(
-                    isMakerSide
-                        ? ExchangeContractErrs.InsufficientMakerFeeAllowance
-                        : ExchangeContractErrs.InsufficientTakerFeeAllowance,
-                );
+                const error = isMakerSide
+                    ? ExchangeContractErrs.InsufficientMakerFeeAllowance
+                    : ExchangeContractErrs.InsufficientTakerFeeAllowance;
+                return { isValid: false, error };
             }
         }
-
-        let minFillableTakerAssetAmountWithinNoRoundingErrorRange;
-        if (isMakerSide) {
-            minFillableTakerAssetAmountWithinNoRoundingErrorRange = signedOrder.takerAssetAmount
-                .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
-                .dividedBy(signedOrder.makerAssetAmount);
-        } else {
-            minFillableTakerAssetAmountWithinNoRoundingErrorRange = signedOrder.makerAssetAmount
-                .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
-                .dividedBy(signedOrder.takerAssetAmount);
-        }
-
-        if (
-            sidedOrderRelevantState.remainingFillableAssetAmount.lessThan(
-                minFillableTakerAssetAmountWithinNoRoundingErrorRange,
-            )
-        ) {
-            throw new Error(ExchangeContractErrs.OrderFillRoundingError);
+        const remainingTakerAssetAmount = signedOrder.takerAssetAmount.minus(
+            sidedOrderRelevantState.filledTakerAssetAmount,
+        );
+        const isRoundingError = OrderValidationUtils.isRoundingErrorFloor(
+            remainingTakerAssetAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.makerAssetAmount,
+        );
+        if (isRoundingError) {
+            return { isValid: false, error: ExchangeContractErrs.OrderFillRoundingError };
         }
+        return { isValid: true };
     }
+    /**
+     * Instantiate OrderStateUtils
+     * @param balanceAndProxyAllowanceFetcher A class that is capable of fetching balances
+     * and proxyAllowances for Ethereum addresses. It must implement AbstractBalanceAndProxyAllowanceFetcher
+     * @param orderFilledCancelledFetcher A class that is capable of fetching whether an order
+     * is cancelled and how much of it has been filled. It must implement AbstractOrderFilledCancelledFetcher
+     * @return Instance of OrderStateUtils
+     */
     constructor(
         balanceAndProxyAllowanceFetcher: AbstractBalanceAndProxyAllowanceFetcher,
         orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher,
@@ -98,9 +106,18 @@ export class OrderStateUtils {
         this._balanceAndProxyAllowanceFetcher = balanceAndProxyAllowanceFetcher;
         this._orderFilledCancelledFetcher = orderFilledCancelledFetcher;
     }
-    public async getOpenOrderStateAsync(signedOrder: SignedOrder): Promise<OrderState> {
+    /**
+     * Get the orderState for an "open" order (i.e where takerAddress=NULL_ADDRESS)
+     * This method will only check the maker's balance/allowance to calculate the
+     * OrderState.
+     * @param signedOrder The order of interest
+     * @return State relevant to the signedOrder, as well as whether the signedOrder is "valid".
+     * Validity is defined as a non-zero amount of the order can still be filled.
+     */
+    public async getOpenOrderStateAsync(signedOrder: SignedOrder, transactionHash?: string): Promise<OrderState> {
         const orderRelevantState = await this.getOpenOrderRelevantStateAsync(signedOrder);
         const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+        const isOrderCancelled = await this._orderFilledCancelledFetcher.isOrderCancelledAsync(orderHash);
         const sidedOrderRelevantState = {
             isMakerSide: true,
             traderBalance: orderRelevantState.makerBalance,
@@ -109,24 +126,32 @@ export class OrderStateUtils {
             traderFeeProxyAllowance: orderRelevantState.makerFeeProxyAllowance,
             filledTakerAssetAmount: orderRelevantState.filledTakerAssetAmount,
             remainingFillableAssetAmount: orderRelevantState.remainingFillableMakerAssetAmount,
+            isOrderCancelled,
         };
-        try {
-            OrderStateUtils._validateIfOrderIsValid(signedOrder, sidedOrderRelevantState);
+        const orderValidationResult = OrderStateUtils._validateIfOrderIsValid(signedOrder, sidedOrderRelevantState);
+        if (orderValidationResult.isValid) {
             const orderState: OrderStateValid = {
                 isValid: true,
                 orderHash,
                 orderRelevantState,
+                transactionHash,
             };
             return orderState;
-        } catch (err) {
+        } else {
             const orderState: OrderStateInvalid = {
                 isValid: false,
                 orderHash,
-                error: err.message,
+                error: orderValidationResult.error,
+                transactionHash,
             };
             return orderState;
         }
     }
+    /**
+     * Get state relevant to an order (i.e makerBalance, makerAllowance, filledTakerAssetAmount, etc...
+     * @param signedOrder Order of interest
+     * @return An instance of OrderRelevantState
+     */
     public async getOpenOrderRelevantStateAsync(signedOrder: SignedOrder): Promise<OrderRelevantState> {
         const isMaker = true;
         const sidedOrderRelevantState = await this._getSidedOrderRelevantStateAsync(
@@ -149,6 +174,12 @@ export class OrderStateUtils {
         };
         return orderRelevantState;
     }
+    /**
+     * Get the max amount of the supplied order's takerAmount that could still be filled
+     * @param signedOrder Order of interest
+     * @param takerAddress Hypothetical taker of the order
+     * @return fillableTakerAssetAmount
+     */
     public async getMaxFillableTakerAssetAmountAsync(
         signedOrder: SignedOrder,
         takerAddress: string,
@@ -162,7 +193,7 @@ export class OrderStateUtils {
         );
         const remainingFillableTakerAssetAmountGivenMakersStatus = signedOrder.makerAssetAmount.eq(0)
             ? new BigNumber(0)
-            : utils.getPartialAmount(
+            : utils.getPartialAmountFloor(
                   orderRelevantMakerState.remainingFillableAssetAmount,
                   signedOrder.makerAssetAmount,
                   signedOrder.takerAssetAmount,
@@ -181,32 +212,6 @@ export class OrderStateUtils {
 
         return fillableTakerAssetAmount;
     }
-    public async getMaxFillableTakerAssetAmountForFailingOrderAsync(
-        signedOrder: SignedOrder,
-        takerAddress: string,
-    ): Promise<BigNumber> {
-        // Get min of taker balance & allowance
-        const takerAssetBalanceOfTaker = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(
-            signedOrder.takerAssetData,
-            takerAddress,
-        );
-        const takerAssetAllowanceOfTaker = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
-            signedOrder.takerAssetData,
-            takerAddress,
-        );
-        const minTakerAssetAmount = BigNumber.min([takerAssetBalanceOfTaker, takerAssetAllowanceOfTaker]);
-
-        // get remainingFillAmount
-        const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
-        const filledTakerAssetAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
-        const remainingFillTakerAssetAmount = signedOrder.takerAssetAmount.minus(filledTakerAssetAmount);
-
-        if (minTakerAssetAmount.gte(remainingFillTakerAssetAmount)) {
-            return remainingFillTakerAssetAmount;
-        } else {
-            return minTakerAssetAmount;
-        }
-    }
     private async _getSidedOrderRelevantStateAsync(
         isMakerSide: boolean,
         signedOrder: SignedOrder,
@@ -278,6 +283,7 @@ export class OrderStateUtils {
             traderFeeProxyAllowance,
             filledTakerAssetAmount,
             remainingFillableAssetAmount,
+            isOrderCancelled,
         };
         return sidedOrderRelevantState;
     }
diff --git a/packages/order-utils/src/order_validation_utils.ts b/packages/order-utils/src/order_validation_utils.ts
index 67d747081..8227fb07c 100644
--- a/packages/order-utils/src/order_validation_utils.ts
+++ b/packages/order-utils/src/order_validation_utils.ts
@@ -9,12 +9,22 @@ import { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_f
 import { constants } from './constants';
 import { ExchangeTransferSimulator } from './exchange_transfer_simulator';
 import { orderHashUtils } from './order_hash';
-import { isValidSignatureAsync } from './signature_utils';
+import { signatureUtils } from './signature_utils';
 import { utils } from './utils';
 
+/**
+ * A utility class for validating orders
+ */
 export class OrderValidationUtils {
     private readonly _orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher;
-    public static isRoundingError(numerator: BigNumber, denominator: BigNumber, target: BigNumber): boolean {
+    /**
+     * A Typescript implementation mirroring the implementation of isRoundingError in the
+     * Exchange smart contract
+     * @param numerator Numerator value. When used to check an order, pass in `takerAssetFilledAmount`
+     * @param denominator Denominator value.  When used to check an order, pass in `order.takerAssetAmount`
+     * @param target Target value. When used to check an order, pass in `order.makerAssetAmount`
+     */
+    public static isRoundingErrorFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): boolean {
         // Solidity's mulmod() in JS
         // Source: https://solidity.readthedocs.io/en/latest/units-and-global-variables.html#mathematical-and-cryptographic-functions
         if (denominator.eq(0)) {
@@ -31,6 +41,15 @@ export class OrderValidationUtils {
         const isError = errPercentageTimes1000000.gt(1000);
         return isError;
     }
+    /**
+     * Validate that the maker & taker have sufficient balances/allowances
+     * to fill the supplied order to the fillTakerAssetAmount amount
+     * @param exchangeTradeEmulator ExchangeTradeEmulator to use
+     * @param signedOrder SignedOrder to test
+     * @param fillTakerAssetAmount Amount of takerAsset to fill the signedOrder
+     * @param senderAddress Sender of the fillOrder tx
+     * @param zrxAssetData AssetData for the ZRX token
+     */
     public static async validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         signedOrder: SignedOrder,
@@ -39,7 +58,7 @@ export class OrderValidationUtils {
         zrxAssetData: string,
     ): Promise<void> {
         try {
-            const fillMakerTokenAmount = utils.getPartialAmount(
+            const fillMakerTokenAmount = utils.getPartialAmountFloor(
                 fillTakerAssetAmount,
                 signedOrder.takerAssetAmount,
                 signedOrder.makerAssetAmount,
@@ -60,7 +79,7 @@ export class OrderValidationUtils {
                 TradeSide.Taker,
                 TransferType.Trade,
             );
-            const makerFeeAmount = utils.getPartialAmount(
+            const makerFeeAmount = utils.getPartialAmountFloor(
                 fillTakerAssetAmount,
                 signedOrder.takerAssetAmount,
                 signedOrder.makerFee,
@@ -73,7 +92,7 @@ export class OrderValidationUtils {
                 TradeSide.Maker,
                 TransferType.Fee,
             );
-            const takerFeeAmount = utils.getPartialAmount(
+            const takerFeeAmount = utils.getPartialAmountFloor(
                 fillTakerAssetAmount,
                 signedOrder.takerAssetAmount,
                 signedOrder.takerFee,
@@ -104,9 +123,22 @@ export class OrderValidationUtils {
             throw new Error(RevertReason.OrderUnfillable);
         }
     }
+    /**
+     * Instantiate OrderValidationUtils
+     * @param orderFilledCancelledFetcher A module that implements the AbstractOrderFilledCancelledFetcher
+     * @return An instance of OrderValidationUtils
+     */
     constructor(orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher) {
         this._orderFilledCancelledFetcher = orderFilledCancelledFetcher;
     }
+    /**
+     * Validate if the supplied order is fillable, and throw if it isn't
+     * @param exchangeTradeEmulator ExchangeTradeEmulator instance
+     * @param signedOrder SignedOrder of interest
+     * @param zrxAssetData ZRX assetData
+     * @param expectedFillTakerTokenAmount If supplied, this call will make sure this amount is fillable.
+     * If it isn't supplied, we check if the order is fillable for a non-zero amount
+     */
     public async validateOrderFillableOrThrowAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         signedOrder: SignedOrder,
@@ -132,6 +164,15 @@ export class OrderValidationUtils {
             zrxAssetData,
         );
     }
+    /**
+     * Validate a call to FillOrder and throw if it wouldn't succeed
+     * @param exchangeTradeEmulator ExchangeTradeEmulator to use
+     * @param provider Web3 provider to use for JSON RPC requests
+     * @param signedOrder SignedOrder of interest
+     * @param fillTakerAssetAmount Amount we'd like to fill the order for
+     * @param takerAddress The taker of the order
+     * @param zrxAssetData ZRX asset data
+     */
     public async validateFillOrderThrowIfInvalidAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         provider: Provider,
@@ -147,7 +188,7 @@ export class OrderValidationUtils {
             throw new Error(RevertReason.InvalidTakerAmount);
         }
         const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
-        const isValid = await isValidSignatureAsync(
+        const isValid = await signatureUtils.isValidSignatureAsync(
             provider,
             orderHash,
             signedOrder.signature,
@@ -177,7 +218,7 @@ export class OrderValidationUtils {
             zrxAssetData,
         );
 
-        const wouldRoundingErrorOccur = OrderValidationUtils.isRoundingError(
+        const wouldRoundingErrorOccur = OrderValidationUtils.isRoundingErrorFloor(
             desiredFillTakerTokenAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerAssetAmount,
@@ -187,6 +228,15 @@ export class OrderValidationUtils {
         }
         return filledTakerTokenAmount;
     }
+    /**
+     * Validate a call to fillOrKillOrder and throw if it would fail
+     * @param exchangeTradeEmulator ExchangeTradeEmulator to use
+     * @param provider Web3 provider to use for JSON RPC requests
+     * @param signedOrder SignedOrder of interest
+     * @param fillTakerAssetAmount Amount we'd like to fill the order for
+     * @param takerAddress The taker of the order
+     * @param zrxAssetData ZRX asset data
+     */
     public async validateFillOrKillOrderThrowIfInvalidAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         provider: Provider,
diff --git a/packages/order-utils/src/parsing_utils.ts b/packages/order-utils/src/parsing_utils.ts
new file mode 100644
index 000000000..232c54b7b
--- /dev/null
+++ b/packages/order-utils/src/parsing_utils.ts
@@ -0,0 +1,27 @@
+import { BigNumber } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+export const orderParsingUtils = {
+    convertStringsFieldsToBigNumbers(obj: any, fields: string[]): any {
+        const result = _.assign({}, obj);
+        _.each(fields, field => {
+            _.update(result, field, (value: string) => {
+                if (_.isUndefined(value)) {
+                    throw new Error(`Could not find field '${field}' while converting string fields to BigNumber.`);
+                }
+                return new BigNumber(value);
+            });
+        });
+        return result;
+    },
+    convertOrderStringFieldsToBigNumber(order: any): any {
+        return orderParsingUtils.convertStringsFieldsToBigNumbers(order, [
+            'makerAssetAmount',
+            'takerAssetAmount',
+            'makerFee',
+            'takerFee',
+            'expirationTimeSeconds',
+            'salt',
+        ]);
+    },
+};
diff --git a/packages/order-utils/src/rate_utils.ts b/packages/order-utils/src/rate_utils.ts
new file mode 100644
index 000000000..c9ca72c59
--- /dev/null
+++ b/packages/order-utils/src/rate_utils.ts
@@ -0,0 +1,48 @@
+import { schemas } from '@0xproject/json-schemas';
+import { Order } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+
+import { assert } from './assert';
+import { constants } from './constants';
+
+export const rateUtils = {
+    /**
+     * Takes an order and calculates the fee adjusted rate (takerAsset/makerAsset) by calculating how much takerAsset
+     * is required to cover the fees (feeRate * takerFee), adding the takerAssetAmount and dividing by makerAssetAmount
+     * @param   order       An object that conforms to the order interface
+     * @param   feeRate     The market rate of ZRX denominated in takerAssetAmount
+     *                      (ex. feeRate is 0.1 takerAsset/ZRX if it takes 1 unit of takerAsset to buy 10 ZRX)
+     *                      Defaults to 0
+     * @return  The rate (takerAsset/makerAsset) of the order adjusted for fees
+     */
+    getFeeAdjustedRateOfOrder(order: Order, feeRate: BigNumber = constants.ZERO_AMOUNT): BigNumber {
+        assert.doesConformToSchema('order', order, schemas.orderSchema);
+        assert.isBigNumber('feeRate', feeRate);
+        assert.assert(
+            feeRate.gte(constants.ZERO_AMOUNT),
+            `Expected feeRate: ${feeRate} to be greater than or equal to 0`,
+        );
+        const takerAssetAmountNeededToPayForFees = order.takerFee.mul(feeRate);
+        const totalTakerAssetAmount = takerAssetAmountNeededToPayForFees.plus(order.takerAssetAmount);
+        const rate = totalTakerAssetAmount.div(order.makerAssetAmount);
+        return rate;
+    },
+    /**
+     * Takes a fee order (makerAssetData corresponds to ZRX and takerAssetData corresponds to WETH) and calculates
+     * the fee adjusted rate (WETH/ZRX) by dividing the takerAssetAmount by the makerAmount minus the takerFee
+     * @param   feeOrder    An object that conforms to the order interface
+     * @return  The rate (WETH/ZRX) of the fee order adjusted for fees
+     */
+    getFeeAdjustedRateOfFeeOrder(feeOrder: Order): BigNumber {
+        assert.doesConformToSchema('feeOrder', feeOrder, schemas.orderSchema);
+        const zrxAmountAfterFees = feeOrder.makerAssetAmount.sub(feeOrder.takerFee);
+        assert.assert(
+            zrxAmountAfterFees.greaterThan(constants.ZERO_AMOUNT),
+            `Expected takerFee: ${JSON.stringify(feeOrder.takerFee)} to be less than makerAssetAmount: ${JSON.stringify(
+                feeOrder.makerAssetAmount,
+            )}`,
+        );
+        const rate = feeOrder.takerAssetAmount.div(zrxAmountAfterFees);
+        return rate;
+    },
+};
diff --git a/packages/order-utils/src/signature_utils.ts b/packages/order-utils/src/signature_utils.ts
index 870aef2ed..3b656d3fc 100644
--- a/packages/order-utils/src/signature_utils.ts
+++ b/packages/order-utils/src/signature_utils.ts
@@ -13,334 +13,334 @@ import { IWalletContract } from './generated_contract_wrappers/i_wallet';
 import { OrderError } from './types';
 import { utils } from './utils';
 
-/**
- * Verifies that the provided signature is valid according to the 0x Protocol smart contracts
- * @param   data          The hex encoded data signed by the supplied signature.
- * @param   signature     A hex encoded 0x Protocol signature made up of: [TypeSpecificData][SignatureType].
- *          E.g [vrs][SignatureType.EIP712]
- * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
- * @return  Whether the signature is valid for the supplied signerAddress and data.
- */
-export async function isValidSignatureAsync(
-    provider: Provider,
-    data: string,
-    signature: string,
-    signerAddress: string,
-): Promise<boolean> {
-    assert.isWeb3Provider('provider', provider);
-    assert.isHexString('data', data);
-    assert.isHexString('signature', signature);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-    const signatureTypeIndexIfExists = utils.getSignatureTypeIndexIfExists(signature);
-    if (_.isUndefined(signatureTypeIndexIfExists)) {
-        throw new Error(`Unrecognized signatureType in signature: ${signature}`);
-    }
+export const signatureUtils = {
+    /**
+     * Verifies that the provided signature is valid according to the 0x Protocol smart contracts
+     * @param   data          The hex encoded data signed by the supplied signature.
+     * @param   signature     A hex encoded 0x Protocol signature made up of: [TypeSpecificData][SignatureType].
+     *          E.g [vrs][SignatureType.EIP712]
+     * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
+     * @return  Whether the signature is valid for the supplied signerAddress and data.
+     */
+    async isValidSignatureAsync(
+        provider: Provider,
+        data: string,
+        signature: string,
+        signerAddress: string,
+    ): Promise<boolean> {
+        assert.isWeb3Provider('provider', provider);
+        assert.isHexString('data', data);
+        assert.isHexString('signature', signature);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        const signatureTypeIndexIfExists = utils.getSignatureTypeIndexIfExists(signature);
+        if (_.isUndefined(signatureTypeIndexIfExists)) {
+            throw new Error(`Unrecognized signatureType in signature: ${signature}`);
+        }
 
-    switch (signatureTypeIndexIfExists) {
-        case SignatureType.Illegal:
-        case SignatureType.Invalid:
-            return false;
+        switch (signatureTypeIndexIfExists) {
+            case SignatureType.Illegal:
+            case SignatureType.Invalid:
+                return false;
 
-        case SignatureType.EIP712: {
-            const ecSignature = parseECSignature(signature);
-            return isValidECSignature(data, ecSignature, signerAddress);
-        }
+            case SignatureType.EIP712: {
+                const ecSignature = signatureUtils.parseECSignature(signature);
+                return signatureUtils.isValidECSignature(data, ecSignature, signerAddress);
+            }
 
-        case SignatureType.EthSign: {
-            const ecSignature = parseECSignature(signature);
-            const prefixedMessageHex = addSignedMessagePrefix(data, SignerType.Default);
-            return isValidECSignature(prefixedMessageHex, ecSignature, signerAddress);
-        }
+            case SignatureType.EthSign: {
+                const ecSignature = signatureUtils.parseECSignature(signature);
+                const prefixedMessageHex = signatureUtils.addSignedMessagePrefix(data, SignerType.Default);
+                return signatureUtils.isValidECSignature(prefixedMessageHex, ecSignature, signerAddress);
+            }
 
-        case SignatureType.Caller:
-            // HACK: We currently do not "validate" the caller signature type.
-            // It can only be validated during Exchange contract execution.
-            throw new Error('Caller signature type cannot be validated off-chain');
+            case SignatureType.Wallet: {
+                const isValid = await signatureUtils.isValidWalletSignatureAsync(
+                    provider,
+                    data,
+                    signature,
+                    signerAddress,
+                );
+                return isValid;
+            }
 
-        case SignatureType.Wallet: {
-            const isValid = await isValidWalletSignatureAsync(provider, data, signature, signerAddress);
-            return isValid;
-        }
+            case SignatureType.Validator: {
+                const isValid = await signatureUtils.isValidValidatorSignatureAsync(
+                    provider,
+                    data,
+                    signature,
+                    signerAddress,
+                );
+                return isValid;
+            }
 
-        case SignatureType.Validator: {
-            const isValid = await isValidValidatorSignatureAsync(provider, data, signature, signerAddress);
-            return isValid;
-        }
+            case SignatureType.PreSigned: {
+                return signatureUtils.isValidPresignedSignatureAsync(provider, data, signerAddress);
+            }
 
-        case SignatureType.PreSigned: {
-            return isValidPresignedSignatureAsync(provider, data, signerAddress);
+            default:
+                throw new Error(`Unhandled SignatureType: ${signatureTypeIndexIfExists}`);
         }
-
-        case SignatureType.Trezor: {
-            const prefixedMessageHex = addSignedMessagePrefix(data, SignerType.Trezor);
-            const ecSignature = parseECSignature(signature);
-            return isValidECSignature(prefixedMessageHex, ecSignature, signerAddress);
+    },
+    /**
+     * Verifies that the provided presigned signature is valid according to the 0x Protocol smart contracts
+     * @param   provider      Web3 provider to use for all JSON RPC requests
+     * @param   data          The hex encoded data signed by the supplied signature
+     * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
+     * @return  Whether the data was preSigned by the supplied signerAddress
+     */
+    async isValidPresignedSignatureAsync(provider: Provider, data: string, signerAddress: string): Promise<boolean> {
+        assert.isWeb3Provider('provider', provider);
+        assert.isHexString('data', data);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        const exchangeContract = new ExchangeContract(artifacts.Exchange.compilerOutput.abi, signerAddress, provider);
+        const isValid = await exchangeContract.preSigned.callAsync(data, signerAddress);
+        return isValid;
+    },
+    /**
+     * Verifies that the provided wallet signature is valid according to the 0x Protocol smart contracts
+     * @param   provider      Web3 provider to use for all JSON RPC requests
+     * @param   data          The hex encoded data signed by the supplied signature.
+     * @param   signature     A hex encoded presigned 0x Protocol signature made up of: [SignatureType.Presigned]
+     * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
+     * @return  Whether the data was preSigned by the supplied signerAddress.
+     */
+    async isValidWalletSignatureAsync(
+        provider: Provider,
+        data: string,
+        signature: string,
+        signerAddress: string,
+    ): Promise<boolean> {
+        assert.isWeb3Provider('provider', provider);
+        assert.isHexString('data', data);
+        assert.isHexString('signature', signature);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        // tslint:disable-next-line:custom-no-magic-numbers
+        const signatureWithoutType = signature.slice(-2);
+        const walletContract = new IWalletContract(artifacts.IWallet.compilerOutput.abi, signerAddress, provider);
+        const isValid = await walletContract.isValidSignature.callAsync(data, signatureWithoutType);
+        return isValid;
+    },
+    /**
+     * Verifies that the provided validator signature is valid according to the 0x Protocol smart contracts
+     * @param   provider      Web3 provider to use for all JSON RPC requests
+     * @param   data          The hex encoded data signed by the supplied signature.
+     * @param   signature     A hex encoded presigned 0x Protocol signature made up of: [SignatureType.Presigned]
+     * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
+     * @return  Whether the data was preSigned by the supplied signerAddress.
+     */
+    async isValidValidatorSignatureAsync(
+        provider: Provider,
+        data: string,
+        signature: string,
+        signerAddress: string,
+    ): Promise<boolean> {
+        assert.isWeb3Provider('provider', provider);
+        assert.isHexString('data', data);
+        assert.isHexString('signature', signature);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        const validatorSignature = parseValidatorSignature(signature);
+        const exchangeContract = new ExchangeContract(artifacts.Exchange.compilerOutput.abi, signerAddress, provider);
+        const isValidatorApproved = await exchangeContract.allowedValidators.callAsync(
+            signerAddress,
+            validatorSignature.validatorAddress,
+        );
+        if (!isValidatorApproved) {
+            throw new Error(
+                `Validator ${validatorSignature.validatorAddress} was not pre-approved by ${signerAddress}.`,
+            );
         }
 
-        default:
-            throw new Error(`Unhandled SignatureType: ${signatureTypeIndexIfExists}`);
-    }
-}
-
-/**
- * Verifies that the provided presigned signature is valid according to the 0x Protocol smart contracts
- * @param   data          The hex encoded data signed by the supplied signature.
- * @param   signature     A hex encoded presigned 0x Protocol signature made up of: [SignatureType.Presigned]
- * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
- * @return  Whether the data was preSigned by the supplied signerAddress.
- */
-export async function isValidPresignedSignatureAsync(
-    provider: Provider,
-    data: string,
-    signerAddress: string,
-): Promise<boolean> {
-    assert.isWeb3Provider('provider', provider);
-    assert.isHexString('data', data);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-    const exchangeContract = new ExchangeContract(artifacts.Exchange.compilerOutput.abi, signerAddress, provider);
-    const isValid = await exchangeContract.preSigned.callAsync(data, signerAddress);
-    return isValid;
-}
-
-/**
- * Verifies that the provided wallet signature is valid according to the 0x Protocol smart contracts
- * @param   data          The hex encoded data signed by the supplied signature.
- * @param   signature     A hex encoded presigned 0x Protocol signature made up of: [SignatureType.Presigned]
- * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
- * @return  Whether the data was preSigned by the supplied signerAddress.
- */
-export async function isValidWalletSignatureAsync(
-    provider: Provider,
-    data: string,
-    signature: string,
-    signerAddress: string,
-): Promise<boolean> {
-    assert.isWeb3Provider('provider', provider);
-    assert.isHexString('data', data);
-    assert.isHexString('signature', signature);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-    // tslint:disable-next-line:custom-no-magic-numbers
-    const signatureWithoutType = signature.slice(-2);
-    const walletContract = new IWalletContract(artifacts.IWallet.compilerOutput.abi, signerAddress, provider);
-    const isValid = await walletContract.isValidSignature.callAsync(data, signatureWithoutType);
-    return isValid;
-}
-
-/**
- * Verifies that the provided validator signature is valid according to the 0x Protocol smart contracts
- * @param   data          The hex encoded data signed by the supplied signature.
- * @param   signature     A hex encoded presigned 0x Protocol signature made up of: [SignatureType.Presigned]
- * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
- * @return  Whether the data was preSigned by the supplied signerAddress.
- */
-export async function isValidValidatorSignatureAsync(
-    provider: Provider,
-    data: string,
-    signature: string,
-    signerAddress: string,
-): Promise<boolean> {
-    assert.isWeb3Provider('provider', provider);
-    assert.isHexString('data', data);
-    assert.isHexString('signature', signature);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-    const validatorSignature = parseValidatorSignature(signature);
-    const exchangeContract = new ExchangeContract(artifacts.Exchange.compilerOutput.abi, signerAddress, provider);
-    const isValidatorApproved = await exchangeContract.allowedValidators.callAsync(
-        signerAddress,
-        validatorSignature.validatorAddress,
-    );
-    if (!isValidatorApproved) {
-        throw new Error(`Validator ${validatorSignature.validatorAddress} was not pre-approved by ${signerAddress}.`);
-    }
-
-    const validatorContract = new IValidatorContract(artifacts.IValidator.compilerOutput.abi, signerAddress, provider);
-    const isValid = await validatorContract.isValidSignature.callAsync(
-        data,
-        signerAddress,
-        validatorSignature.signature,
-    );
-    return isValid;
-}
-
-/**
- * Checks if the supplied elliptic curve signature corresponds to signing `data` with
- * the private key corresponding to `signerAddress`
- * @param   data          The hex encoded data signed by the supplied signature.
- * @param   signature     An object containing the elliptic curve signature parameters.
- * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
- * @return Whether the ECSignature is valid.
- */
-export function isValidECSignature(data: string, signature: ECSignature, signerAddress: string): boolean {
-    assert.isHexString('data', data);
-    assert.doesConformToSchema('signature', signature, schemas.ecSignatureSchema);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-
-    const msgHashBuff = ethUtil.toBuffer(data);
-    try {
-        const pubKey = ethUtil.ecrecover(
-            msgHashBuff,
-            signature.v,
-            ethUtil.toBuffer(signature.r),
-            ethUtil.toBuffer(signature.s),
+        const validatorContract = new IValidatorContract(
+            artifacts.IValidator.compilerOutput.abi,
+            signerAddress,
+            provider,
         );
-        const retrievedAddress = ethUtil.bufferToHex(ethUtil.pubToAddress(pubKey));
-        return retrievedAddress === signerAddress;
-    } catch (err) {
-        return false;
-    }
-}
-
-/**
- * Signs an orderHash and returns it's elliptic curve signature and signature type.
- * This method currently supports TestRPC, Geth and Parity above and below V1.6.6
- * @param   orderHash       Hex encoded orderHash to sign.
- * @param   signerAddress   The hex encoded Ethereum address you wish to sign it with. This address
- *          must be available via the Provider supplied to 0x.js.
- * @param   signerType Different signers add/require different prefixes to be prepended to the message being signed.
- *          Since we cannot know ahead of time which signer you are using, you must supply a SignerType.
- * @return  A hex encoded string containing the Elliptic curve signature generated by signing the orderHash and the Signature Type.
- */
-export async function ecSignOrderHashAsync(
-    provider: Provider,
-    orderHash: string,
-    signerAddress: string,
-    signerType: SignerType,
-): Promise<string> {
-    assert.isWeb3Provider('provider', provider);
-    assert.isHexString('orderHash', orderHash);
-    assert.isETHAddressHex('signerAddress', signerAddress);
-    const web3Wrapper = new Web3Wrapper(provider);
-    await assert.isSenderAddressAsync('signerAddress', signerAddress, web3Wrapper);
-    const normalizedSignerAddress = signerAddress.toLowerCase();
-
-    let msgHashHex = orderHash;
-    const prefixedMsgHashHex = addSignedMessagePrefix(orderHash, signerType);
-    // Metamask incorrectly implements eth_sign and does not prefix the message as per the spec
-    // Source: https://github.com/MetaMask/metamask-extension/commit/a9d36860bec424dcee8db043d3e7da6a5ff5672e
-    if (signerType === SignerType.Metamask) {
-        msgHashHex = prefixedMsgHashHex;
-    }
-    const signature = await web3Wrapper.signMessageAsync(normalizedSignerAddress, msgHashHex);
+        const isValid = await validatorContract.isValidSignature.callAsync(
+            data,
+            signerAddress,
+            validatorSignature.signature,
+        );
+        return isValid;
+    },
+    /**
+     * Checks if the supplied elliptic curve signature corresponds to signing `data` with
+     * the private key corresponding to `signerAddress`
+     * @param   data          The hex encoded data signed by the supplied signature.
+     * @param   signature     An object containing the elliptic curve signature parameters.
+     * @param   signerAddress The hex encoded address that signed the data, producing the supplied signature.
+     * @return Whether the ECSignature is valid.
+     */
+    isValidECSignature(data: string, signature: ECSignature, signerAddress: string): boolean {
+        assert.isHexString('data', data);
+        assert.doesConformToSchema('signature', signature, schemas.ecSignatureSchema);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        const normalizedSignerAddress = signerAddress.toLowerCase();
 
-    // HACK: There is no consensus on whether the signatureHex string should be formatted as
-    // v + r + s OR r + s + v, and different clients (even different versions of the same client)
-    // return the signature params in different orders. In order to support all client implementations,
-    // we parse the signature in both ways, and evaluate if either one is a valid signature.
-    // r + s + v is the most prevalent format from eth_sign, so we attempt this first.
-    // tslint:disable-next-line:custom-no-magic-numbers
-    const validVParamValues = [27, 28];
-    const ecSignatureRSV = parseSignatureHexAsRSV(signature);
-    if (_.includes(validVParamValues, ecSignatureRSV.v)) {
-        const isValidRSVSignature = isValidECSignature(prefixedMsgHashHex, ecSignatureRSV, normalizedSignerAddress);
-        if (isValidRSVSignature) {
-            const convertedSignatureHex = convertECSignatureToSignatureHex(ecSignatureRSV, signerType);
-            return convertedSignatureHex;
+        const msgHashBuff = ethUtil.toBuffer(data);
+        try {
+            const pubKey = ethUtil.ecrecover(
+                msgHashBuff,
+                signature.v,
+                ethUtil.toBuffer(signature.r),
+                ethUtil.toBuffer(signature.s),
+            );
+            const retrievedAddress = ethUtil.bufferToHex(ethUtil.pubToAddress(pubKey));
+            const normalizedRetrievedAddress = retrievedAddress.toLowerCase();
+            return normalizedRetrievedAddress === normalizedSignerAddress;
+        } catch (err) {
+            return false;
         }
-    }
-    const ecSignatureVRS = parseSignatureHexAsVRS(signature);
-    if (_.includes(validVParamValues, ecSignatureVRS.v)) {
-        const isValidVRSSignature = isValidECSignature(prefixedMsgHashHex, ecSignatureVRS, normalizedSignerAddress);
-        if (isValidVRSSignature) {
-            const convertedSignatureHex = convertECSignatureToSignatureHex(ecSignatureVRS, signerType);
-            return convertedSignatureHex;
+    },
+    /**
+     * Signs an orderHash and returns it's elliptic curve signature and signature type.
+     * This method currently supports TestRPC, Geth and Parity above and below V1.6.6
+     * @param   orderHash       Hex encoded orderHash to sign.
+     * @param   signerAddress   The hex encoded Ethereum address you wish to sign it with. This address
+     *          must be available via the Provider supplied to 0x.js.
+     * @param   signerType Different signers add/require different prefixes to be prepended to the message being signed.
+     *          Since we cannot know ahead of time which signer you are using, you must supply a SignerType.
+     * @return  A hex encoded string containing the Elliptic curve signature generated by signing the orderHash and the Signature Type.
+     */
+    async ecSignOrderHashAsync(
+        provider: Provider,
+        orderHash: string,
+        signerAddress: string,
+        signerType: SignerType,
+    ): Promise<string> {
+        assert.isWeb3Provider('provider', provider);
+        assert.isHexString('orderHash', orderHash);
+        assert.isETHAddressHex('signerAddress', signerAddress);
+        const web3Wrapper = new Web3Wrapper(provider);
+        await assert.isSenderAddressAsync('signerAddress', signerAddress, web3Wrapper);
+        const normalizedSignerAddress = signerAddress.toLowerCase();
+
+        let msgHashHex = orderHash;
+        const prefixedMsgHashHex = signatureUtils.addSignedMessagePrefix(orderHash, signerType);
+        // Metamask incorrectly implements eth_sign and does not prefix the message as per the spec
+        // Source: https://github.com/MetaMask/metamask-extension/commit/a9d36860bec424dcee8db043d3e7da6a5ff5672e
+        if (signerType === SignerType.Metamask) {
+            msgHashHex = prefixedMsgHashHex;
         }
-    }
+        const signature = await web3Wrapper.signMessageAsync(normalizedSignerAddress, msgHashHex);
 
-    throw new Error(OrderError.InvalidSignature);
-}
-/**
- * Combines ECSignature with V,R,S and the relevant signature type for use in 0x protocol
- * @param ecSignature The ECSignature of the signed data
- * @param signerType The SignerType of the signed data
- * @return Hex encoded string of signature (v,r,s) with Signature Type
- */
-export function convertECSignatureToSignatureHex(ecSignature: ECSignature, signerType: SignerType): string {
-    const signatureBuffer = Buffer.concat([
-        ethUtil.toBuffer(ecSignature.v),
-        ethUtil.toBuffer(ecSignature.r),
-        ethUtil.toBuffer(ecSignature.s),
-    ]);
-    const signatureHex = `0x${signatureBuffer.toString('hex')}`;
-    let signatureType;
-    switch (signerType) {
-        case SignerType.Metamask:
-        case SignerType.Ledger:
-        case SignerType.Default: {
-            signatureType = SignatureType.EthSign;
-            break;
+        // HACK: There is no consensus on whether the signatureHex string should be formatted as
+        // v + r + s OR r + s + v, and different clients (even different versions of the same client)
+        // return the signature params in different orders. In order to support all client implementations,
+        // we parse the signature in both ways, and evaluate if either one is a valid signature.
+        // r + s + v is the most prevalent format from eth_sign, so we attempt this first.
+        // tslint:disable-next-line:custom-no-magic-numbers
+        const validVParamValues = [27, 28];
+        const ecSignatureRSV = parseSignatureHexAsRSV(signature);
+        if (_.includes(validVParamValues, ecSignatureRSV.v)) {
+            const isValidRSVSignature = signatureUtils.isValidECSignature(
+                prefixedMsgHashHex,
+                ecSignatureRSV,
+                normalizedSignerAddress,
+            );
+            if (isValidRSVSignature) {
+                const convertedSignatureHex = signatureUtils.convertECSignatureToSignatureHex(
+                    ecSignatureRSV,
+                    signerType,
+                );
+                return convertedSignatureHex;
+            }
         }
-        case SignerType.Trezor: {
-            signatureType = SignatureType.Trezor;
-            break;
+        const ecSignatureVRS = parseSignatureHexAsVRS(signature);
+        if (_.includes(validVParamValues, ecSignatureVRS.v)) {
+            const isValidVRSSignature = signatureUtils.isValidECSignature(
+                prefixedMsgHashHex,
+                ecSignatureVRS,
+                normalizedSignerAddress,
+            );
+            if (isValidVRSSignature) {
+                const convertedSignatureHex = signatureUtils.convertECSignatureToSignatureHex(
+                    ecSignatureVRS,
+                    signerType,
+                );
+                return convertedSignatureHex;
+            }
         }
-        default:
-            throw new Error(`Unrecognized SignerType: ${signerType}`);
-    }
-    const signatureWithType = convertToSignatureWithType(signatureHex, signatureType);
-    return signatureWithType;
-}
-/**
- * Combines the signature proof and the Signature Type.
- * @param signature The hex encoded signature proof
- * @param signatureType The signature type, i.e EthSign, Trezor, Wallet etc.
- * @return Hex encoded string of signature proof with Signature Type
- */
-export function convertToSignatureWithType(signature: string, signatureType: SignatureType): string {
-    const signatureBuffer = Buffer.concat([ethUtil.toBuffer(signature), ethUtil.toBuffer(signatureType)]);
-    const signatureHex = `0x${signatureBuffer.toString('hex')}`;
-    return signatureHex;
-}
-/**
- * Adds the relevant prefix to the message being signed.
- * @param message Message to sign
- * @param signerType The type of message prefix to add for a given SignerType. Different signers expect
- *                          specific message prefixes.
- * @return Prefixed message
- */
-export function addSignedMessagePrefix(message: string, signerType: SignerType = SignerType.Default): string {
-    assert.isString('message', message);
-    assert.doesBelongToStringEnum('signerType', signerType, SignerType);
-    switch (signerType) {
-        case SignerType.Metamask:
-        case SignerType.Ledger:
-        case SignerType.Default: {
-            const msgBuff = ethUtil.toBuffer(message);
-            const prefixedMsgBuff = ethUtil.hashPersonalMessage(msgBuff);
-            const prefixedMsgHex = ethUtil.bufferToHex(prefixedMsgBuff);
-            return prefixedMsgHex;
+
+        throw new Error(OrderError.InvalidSignature);
+    },
+    /**
+     * Combines ECSignature with V,R,S and the relevant signature type for use in 0x protocol
+     * @param ecSignature The ECSignature of the signed data
+     * @param signerType The SignerType of the signed data
+     * @return Hex encoded string of signature (v,r,s) with Signature Type
+     */
+    convertECSignatureToSignatureHex(ecSignature: ECSignature, signerType: SignerType): string {
+        const signatureBuffer = Buffer.concat([
+            ethUtil.toBuffer(ecSignature.v),
+            ethUtil.toBuffer(ecSignature.r),
+            ethUtil.toBuffer(ecSignature.s),
+        ]);
+        const signatureHex = `0x${signatureBuffer.toString('hex')}`;
+        let signatureType;
+        switch (signerType) {
+            case SignerType.Metamask:
+            case SignerType.Ledger:
+            case SignerType.Default: {
+                signatureType = SignatureType.EthSign;
+                break;
+            }
+            default:
+                throw new Error(`Unrecognized SignerType: ${signerType}`);
         }
-        case SignerType.Trezor: {
-            const msgBuff = ethUtil.toBuffer(message);
-            const prefixedMsgBuff = hashTrezorPersonalMessage(msgBuff);
-            const prefixedMsgHex = ethUtil.bufferToHex(prefixedMsgBuff);
-            return prefixedMsgHex;
+        const signatureWithType = signatureUtils.convertToSignatureWithType(signatureHex, signatureType);
+        return signatureWithType;
+    },
+    /**
+     * Combines the signature proof and the Signature Type.
+     * @param signature The hex encoded signature proof
+     * @param signatureType The signature type, i.e EthSign, Wallet etc.
+     * @return Hex encoded string of signature proof with Signature Type
+     */
+    convertToSignatureWithType(signature: string, signatureType: SignatureType): string {
+        const signatureBuffer = Buffer.concat([ethUtil.toBuffer(signature), ethUtil.toBuffer(signatureType)]);
+        const signatureHex = `0x${signatureBuffer.toString('hex')}`;
+        return signatureHex;
+    },
+    /**
+     * Adds the relevant prefix to the message being signed.
+     * @param message Message to sign
+     * @param signerType The type of message prefix to add for a given SignerType. Different signers expect
+     *                          specific message prefixes.
+     * @return Prefixed message
+     */
+    addSignedMessagePrefix(message: string, signerType: SignerType = SignerType.Default): string {
+        assert.isString('message', message);
+        assert.doesBelongToStringEnum('signerType', signerType, SignerType);
+        switch (signerType) {
+            case SignerType.Metamask:
+            case SignerType.Ledger:
+            case SignerType.Default: {
+                const msgBuff = ethUtil.toBuffer(message);
+                const prefixedMsgBuff = ethUtil.hashPersonalMessage(msgBuff);
+                const prefixedMsgHex = ethUtil.bufferToHex(prefixedMsgBuff);
+                return prefixedMsgHex;
+            }
+            default:
+                throw new Error(`Unrecognized SignerType: ${signerType}`);
         }
-        default:
-            throw new Error(`Unrecognized SignerType: ${signerType}`);
-    }
-}
+    },
+    /**
+     * Parse a 0x protocol hex-encoded signature string into it's ECSignature components
+     * @param signature A hex encoded ecSignature 0x Protocol signature
+     * @return An ECSignature object with r,s,v parameters
+     */
+    parseECSignature(signature: string): ECSignature {
+        assert.isHexString('signature', signature);
+        const ecSignatureTypes = [SignatureType.EthSign, SignatureType.EIP712];
+        assert.isOneOfExpectedSignatureTypes(signature, ecSignatureTypes);
 
-/**
- * Parse a 0x protocol hex-encoded signature string into it's ECSignature components
- * @param signature A hex encoded ecSignature 0x Protocol signature
- * @return An ECSignature object with r,s,v parameters
- */
-export function parseECSignature(signature: string): ECSignature {
-    assert.isHexString('signature', signature);
-    const ecSignatureTypes = [SignatureType.EthSign, SignatureType.EIP712, SignatureType.Trezor];
-    assert.isOneOfExpectedSignatureTypes(signature, ecSignatureTypes);
+        // tslint:disable-next-line:custom-no-magic-numbers
+        const vrsHex = signature.slice(0, -2);
+        const ecSignature = parseSignatureHexAsVRS(vrsHex);
 
-    // tslint:disable-next-line:custom-no-magic-numbers
-    const vrsHex = signature.slice(0, -2);
-    const ecSignature = parseSignatureHexAsVRS(vrsHex);
-
-    return ecSignature;
-}
-
-function hashTrezorPersonalMessage(message: Buffer): Buffer {
-    const prefix = ethUtil.toBuffer('\x19Ethereum Signed Message:\n' + String.fromCharCode(message.byteLength));
-    return ethUtil.sha3(Buffer.concat([prefix, message]));
-}
+        return ecSignature;
+    },
+};
 
 function parseValidatorSignature(signature: string): ValidatorSignature {
     assert.isOneOfExpectedSignatureTypes(signature, [SignatureType.Validator]);
diff --git a/packages/order-utils/src/sorting_utils.ts b/packages/order-utils/src/sorting_utils.ts
new file mode 100644
index 000000000..cd5163cf6
--- /dev/null
+++ b/packages/order-utils/src/sorting_utils.ts
@@ -0,0 +1,54 @@
+import { schemas } from '@0xproject/json-schemas';
+import { Order } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+import { assert } from './assert';
+import { constants } from './constants';
+import { rateUtils } from './rate_utils';
+
+export const sortingUtils = {
+    /**
+     * Takes an array of orders and sorts them by takerAsset/makerAsset rate in ascending order (best rate first).
+     * Adjusts the rate of each order according to the feeRate and takerFee for that order.
+     * @param   orders      An array of objects that extend the Order interface. All orders should specify ZRX as
+     *                      the makerAsset and WETH as the takerAsset.
+     * @param   feeRate     The market rate of ZRX denominated in takerAssetAmount
+     *                      (ex. feeRate is 0.1 takerAsset/ZRX if it takes 1 unit of takerAsset to buy 10 ZRX)
+     *                      Defaults to 0
+     * @return  The input orders sorted by rate in ascending order
+     */
+    sortOrdersByFeeAdjustedRate<T extends Order>(orders: T[], feeRate: BigNumber = constants.ZERO_AMOUNT): T[] {
+        assert.doesConformToSchema('orders', orders, schemas.ordersSchema);
+        assert.isBigNumber('feeRate', feeRate);
+        const rateCalculator = (order: Order) => rateUtils.getFeeAdjustedRateOfOrder(order, feeRate);
+        const sortedOrders = sortOrders(orders, rateCalculator);
+        return sortedOrders;
+    },
+    /**
+     * Takes an array of fee orders (makerAssetData corresponds to ZRX and takerAssetData corresponds to WETH)
+     * and sorts them by rate in ascending order (best rate first). Adjusts the rate according to the takerFee.
+     * @param   feeOrders       An array of objects that extend the Order interface. All orders should specify ZRX as
+     *                          the makerAsset and WETH as the takerAsset.
+     * @return  The input orders sorted by rate in ascending order
+     */
+    sortFeeOrdersByFeeAdjustedRate<T extends Order>(feeOrders: T[]): T[] {
+        assert.doesConformToSchema('feeOrders', feeOrders, schemas.ordersSchema);
+        const rateCalculator = rateUtils.getFeeAdjustedRateOfFeeOrder.bind(rateUtils);
+        const sortedOrders = sortOrders(feeOrders, rateCalculator);
+        return sortedOrders;
+    },
+};
+
+type RateCalculator = (order: Order) => BigNumber;
+
+// takes an array of orders, copies them, and sorts the copy based on the rate definition provided by rateCalculator
+function sortOrders<T extends Order>(orders: T[], rateCalculator: RateCalculator): T[] {
+    const copiedOrders = _.cloneDeep(orders);
+    copiedOrders.sort((firstOrder, secondOrder) => {
+        const firstOrderRate = rateCalculator(firstOrder);
+        const secondOrderRate = rateCalculator(secondOrder);
+        return firstOrderRate.comparedTo(secondOrderRate);
+    });
+    return copiedOrders;
+}
diff --git a/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts b/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
index 5a2c1d7ff..8a65178b0 100644
--- a/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
+++ b/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
@@ -21,11 +21,21 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
             [userAddress: string]: BigNumber;
         };
     };
+    /**
+     * Instantiates a BalanceAndProxyAllowanceLazyStore
+     * @param balanceAndProxyAllowanceFetcher  Class the implements the AbstractBalanceAndProxyAllowanceFetcher
+     * @return Instance of BalanceAndProxyAllowanceLazyStore
+     */
     constructor(balanceAndProxyAllowanceFetcher: AbstractBalanceAndProxyAllowanceFetcher) {
         this._balanceAndProxyAllowanceFetcher = balanceAndProxyAllowanceFetcher;
         this._balance = {};
         this._proxyAllowance = {};
     }
+    /**
+     * Get a users balance of an asset
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public async getBalanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
         if (_.isUndefined(this._balance[assetData]) || _.isUndefined(this._balance[assetData][userAddress])) {
             const balance = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(assetData, userAddress);
@@ -34,12 +44,22 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
         const cachedBalance = this._balance[assetData][userAddress];
         return cachedBalance;
     }
+    /**
+     * Set the balance of an asset for a user
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public setBalance(assetData: string, userAddress: string, balance: BigNumber): void {
         if (_.isUndefined(this._balance[assetData])) {
             this._balance[assetData] = {};
         }
         this._balance[assetData][userAddress] = balance;
     }
+    /**
+     * Clear the balance of an asset for a user
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public deleteBalance(assetData: string, userAddress: string): void {
         if (!_.isUndefined(this._balance[assetData])) {
             delete this._balance[assetData][userAddress];
@@ -48,6 +68,11 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
             }
         }
     }
+    /**
+     * Get the 0x asset proxy allowance
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public async getProxyAllowanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
         if (
             _.isUndefined(this._proxyAllowance[assetData]) ||
@@ -62,12 +87,22 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
         const cachedProxyAllowance = this._proxyAllowance[assetData][userAddress];
         return cachedProxyAllowance;
     }
+    /**
+     * Set the 0x asset proxy allowance
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public setProxyAllowance(assetData: string, userAddress: string, proxyAllowance: BigNumber): void {
         if (_.isUndefined(this._proxyAllowance[assetData])) {
             this._proxyAllowance[assetData] = {};
         }
         this._proxyAllowance[assetData][userAddress] = proxyAllowance;
     }
+    /**
+     * Clear the 0x asset proxy allowance
+     * @param assetData AssetData of interest
+     * @param userAddress Ethereum address of interest
+     */
     public deleteProxyAllowance(assetData: string, userAddress: string): void {
         if (!_.isUndefined(this._proxyAllowance[assetData])) {
             delete this._proxyAllowance[assetData][userAddress];
@@ -76,6 +111,11 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
             }
         }
     }
+    /**
+     * Clear all ERC721 0x proxy allowances a user has on all items of a specific ERC721 contract
+     * @param tokenAddress ERc721 token address
+     * @param userAddress Owner Ethereum address
+     */
     public deleteAllERC721ProxyAllowance(tokenAddress: string, userAddress: string): void {
         for (const assetData in this._proxyAllowance) {
             if (this._proxyAllowance.hasOwnProperty(assetData)) {
@@ -90,6 +130,9 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
             }
         }
     }
+    /**
+     * Delete all balances & allowances
+     */
     public deleteAll(): void {
         this._balance = {};
         this._proxyAllowance = {};
diff --git a/packages/order-utils/src/store/order_filled_cancelled_lazy_store.ts b/packages/order-utils/src/store/order_filled_cancelled_lazy_store.ts
index 336c6d0ba..6155c2064 100644
--- a/packages/order-utils/src/store/order_filled_cancelled_lazy_store.ts
+++ b/packages/order-utils/src/store/order_filled_cancelled_lazy_store.ts
@@ -15,11 +15,21 @@ export class OrderFilledCancelledLazyStore implements AbstractOrderFilledCancell
     private _isCancelled: {
         [orderHash: string]: boolean;
     };
+    /**
+     * Instantiate a OrderFilledCancelledLazyStore
+     * @param orderFilledCancelledFetcher Class instance that implements the AbstractOrderFilledCancelledFetcher
+     * @returns An instance of OrderFilledCancelledLazyStore
+     */
     constructor(orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher) {
         this._orderFilledCancelledFetcher = orderFilledCancelledFetcher;
         this._filledTakerAmount = {};
         this._isCancelled = {};
     }
+    /**
+     * Get the filledTakerAssetAmount of an order
+     * @param orderHash OrderHash from order of interest
+     * @return filledTakerAssetAmount
+     */
     public async getFilledTakerAmountAsync(orderHash: string): Promise<BigNumber> {
         if (_.isUndefined(this._filledTakerAmount[orderHash])) {
             const filledTakerAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
@@ -28,12 +38,26 @@ export class OrderFilledCancelledLazyStore implements AbstractOrderFilledCancell
         const cachedFilledTakerAmount = this._filledTakerAmount[orderHash];
         return cachedFilledTakerAmount;
     }
+    /**
+     * Set the filledTakerAssetAmount of an order
+     * @param orderHash OrderHash from order of interest
+     * @param filledTakerAmount Desired filledTakerAssetAmount
+     */
     public setFilledTakerAmount(orderHash: string, filledTakerAmount: BigNumber): void {
         this._filledTakerAmount[orderHash] = filledTakerAmount;
     }
+    /**
+     * Clear the filledTakerAssetAmount of an order
+     * @param orderHash OrderHash from order of interest
+     */
     public deleteFilledTakerAmount(orderHash: string): void {
         delete this._filledTakerAmount[orderHash];
     }
+    /**
+     * Check if an order has been cancelled
+     * @param orderHash OrderHash from order of interest
+     * @return Whether the order has been cancelled
+     */
     public async getIsCancelledAsync(orderHash: string): Promise<boolean> {
         if (_.isUndefined(this._isCancelled[orderHash])) {
             const isCancelled = await this._orderFilledCancelledFetcher.isOrderCancelledAsync(orderHash);
@@ -42,22 +66,43 @@ export class OrderFilledCancelledLazyStore implements AbstractOrderFilledCancell
         const cachedIsCancelled = this._isCancelled[orderHash]; // tslint:disable-line:boolean-naming
         return cachedIsCancelled;
     }
+    /**
+     * Set whether an order has been cancelled or not
+     * @param orderHash OrderHash from order of interest
+     * @param isCancelled Whether this order should be cancelled or not
+     */
     public setIsCancelled(orderHash: string, isCancelled: boolean): void {
         this._isCancelled[orderHash] = isCancelled;
     }
+    /**
+     * Clear whether the order has been cancelled if already set
+     * @param orderHash OrderHash from order of interest
+     */
     public deleteIsCancelled(orderHash: string): void {
         delete this._isCancelled[orderHash];
     }
+    /**
+     * Clear all filled/cancelled state
+     */
     public deleteAll(): void {
         this.deleteAllFilled();
         this.deleteAllIsCancelled();
     }
+    /**
+     * Clear all cancelled state
+     */
     public deleteAllIsCancelled(): void {
         this._isCancelled = {};
     }
+    /**
+     * Clear all filled state
+     */
     public deleteAllFilled(): void {
         this._filledTakerAmount = {};
     }
+    /**
+     * Get the ZRX assetData
+     */
     public getZRXAssetData(): string {
         const zrxAssetData = this._orderFilledCancelledFetcher.getZRXAssetData();
         return zrxAssetData;
diff --git a/packages/order-utils/src/types.ts b/packages/order-utils/src/types.ts
index 1fbd8cf7b..a843efaa4 100644
--- a/packages/order-utils/src/types.ts
+++ b/packages/order-utils/src/types.ts
@@ -41,3 +41,43 @@ export interface CreateOrderOpts {
     salt?: BigNumber;
     expirationTimeSeconds?: BigNumber;
 }
+
+/**
+ * remainingFillableMakerAssetAmount: An array of BigNumbers corresponding to the `orders` parameter.
+ * You can use `OrderStateUtils` `@0xproject/order-utils` to perform blockchain lookups for these values.
+ * Defaults to `makerAssetAmount` values from the orders param.
+ * slippageBufferAmount: An additional amount of makerAsset to be covered by the result in case of trade collisions or partial fills.
+ * Defaults to 0
+ */
+export interface FindOrdersThatCoverMakerAssetFillAmountOpts {
+    remainingFillableMakerAssetAmounts?: BigNumber[];
+    slippageBufferAmount?: BigNumber;
+}
+
+/**
+ * remainingFillableMakerAssetAmount: An array of BigNumbers corresponding to the `orders` parameter.
+ * You can use `OrderStateUtils` `@0xproject/order-utils` to perform blockchain lookups for these values.
+ * Defaults to `makerAssetAmount` values from the orders param.
+ * remainingFillableFeeAmounts: An array of BigNumbers corresponding to the feeOrders parameter.
+ * You can use OrderStateUtils @0xproject/order-utils to perform blockchain lookups for these values.
+ * Defaults to `makerAssetAmount` values from the feeOrders param.
+ * slippageBufferAmount: An additional amount of fee to be covered by the result in case of trade collisions or partial fills.
+ * Defaults to 0
+ */
+export interface FindFeeOrdersThatCoverFeesForTargetOrdersOpts {
+    remainingFillableMakerAssetAmounts?: BigNumber[];
+    remainingFillableFeeAmounts?: BigNumber[];
+    slippageBufferAmount?: BigNumber;
+}
+
+export interface FeeOrdersAndRemainingFeeAmount<T> {
+    resultFeeOrders: T[];
+    feeOrdersRemainingFillableMakerAssetAmounts: BigNumber[];
+    remainingFeeAmount: BigNumber;
+}
+
+export interface OrdersAndRemainingFillAmount<T> {
+    resultOrders: T[];
+    ordersRemainingFillableMakerAssetAmounts: BigNumber[];
+    remainingFillAmount: BigNumber;
+}
diff --git a/packages/order-utils/src/utils.ts b/packages/order-utils/src/utils.ts
index 7aaaf0609..0ff05e8ed 100644
--- a/packages/order-utils/src/utils.ts
+++ b/packages/order-utils/src/utils.ts
@@ -12,7 +12,7 @@ export const utils = {
         const milisecondsInSecond = 1000;
         return new BigNumber(Date.now() / milisecondsInSecond).round();
     },
-    getPartialAmount(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+    getPartialAmountFloor(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
         const fillMakerTokenAmount = numerator
             .mul(target)
             .div(denominator)