Integrating the Auto Router

You can use the Auto Router to fetch optimized trade routes for swapping on Uniswap. To use the Auto Router, you will create an AlphaRouter instance and use the method route to get quotes, gas information, and calldata for an optimized swap.

In this quick start you will:

1. Import necessary packages
2. Initialize the AlphaRouter
3. Set up the parameters for the route method
4. Call route to retrieve calldata
5. Submit a route transaction

Importing the Package

To integrate with the Auto Router, you will use the smart-order-router package. The smart-order-router package allows you to use the Auto Router through the AlphaRouter class.

Import AlphaRouter from the smart-order-router package to get started.

import { AlphaRouter } from '@uniswap/smart-order-router'

Initializing the AlphaRouter

The AlphaRouter class contains methods for generating optimized routes. To create an instance of the AlphaRouter, configure the chainId and provider parameters.

Parameters

Name	Requirement	Description
chainId	[required]	The id of the chain you want to route swaps on. e.g., The chainId for Ethereum mainnet is 1.
provider	[required]	A JSON RPC endpoint, e.g., Infura.

const router = new AlphaRouter({ chainId: 1, provider: web3Provider })

Calling route

The route method returns all the swap calldata and gas information needed for submitting an optimal swap to the chain.

Once you instantiate AlphaRouter call route with the following parameters:

    {
      amount: CurrencyAmount,
      quoteCurrency: Currency,
      tradeType: TradeType,
      swapConfig?: SwapConfig,
      partialRoutingConfig?: Partial<AlphaRouterConfig> = {}
    }

Parameters

Name	Requirement	Description
amount	[required]	The amount specified by the user. For EXACT_INPUT swaps, this is the input token amount. For EXACT_OUTPUT swaps, this is the output token.
quoteCurrency	[required]	The currency of the token we are returning a quote for. For EXACT_INPUT swaps, this is the output token. For EXACT_OUTPUT, this is the input token
swapType	[required]	Either an exactInput swap or an exactOutput swap.
swapConfig	[optional]	Configure to set a recipient, slippageTolerance, deadline, and inputTokenPermit. If provided, calldata for executing the swap will also be returned.
routingConfig	[optional]	Optional config for tuning the performance of the routing algorithm.

This example gets a route for a WETH-USDC swap.

const WETH = new Token(1, '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2', 18, 'WETH', 'Wrapped Ether')

const USDC = new Token(ChainId.MAINNET, '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', 6, 'USDC', 'USD//C')

const route = await router.route(wethAmount, USDC, TradeType.EXACT_INPUT, {
  recipient: myAddress,
  slippageTolerance: new Percent(5, 100),
  deadline: Math.floor(Date.now() / 1000 + 1800),
})

Submitting a Transaction

The object returned from calling route is a SwapRoute object with the following fields:

export type SwapRoute = {
  quote: CurrencyAmount
  quoteGasAdjusted: CurrencyAmount
  estimatedGasUsed: BigNumber
  estimatedGasUsedQuoteToken: CurrencyAmount
  estimatedGasUsedUSD: CurrencyAmount
  gasPriceWei: BigNumber
  trade: Trade<Currency, Currency, TradeType>
  route: RouteWithValidQuote[]
  blockNumber: BigNumber
  methodParameters?: MethodParameters
}

Use the quoted gas price and generated call data as inputs for the transaction, as done below:

const V3_SWAP_ROUTER_ADDRESS = "0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45";
const MY_ADDRESS = /*YOUR ADDRESS HERE*/;

const transaction = {
  data: route.methodParameters.calldata,
  to: V3_SWAP_ROUTER_ADDRESS,
  value: BigNumber.from(route.methodParameters.value),
  from: MY_ADDRESS,
  gasPrice: BigNumber.from(route.gasPriceWei),
};

await web3Provider.sendTransaction(transaction);

The Full Example

This full example compiles all of the steps above and also prints the route quote and gas quotes returned from the SwapRoute data.

import { AlphaRouter } from '@uniswap/smart-order-router'
import { Token, CurrencyAmount } from '@uniswap/sdk-core'

const V3_SWAP_ROUTER_ADDRESS = '0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45';
const MY_ADDRESS = /*YOUR ADDRESS HERE*/;
const web3Provider = /*YOUR PROVIDER HERE*/

const router = new AlphaRouter({ chainId: 1, provider: web3Provider });

const WETH = new Token(
  1,
  '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2',
  18,
  'WETH',
  'Wrapped Ether'
);

const USDC = new Token(
  ChainId.MAINNET,
  '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
  6,
  'USDC',
  'USD//C'
);

const typedValueParsed = '100000000000000000000'
const wethAmount = CurrencyAmount.fromRawAmount(currency, JSBI.BigInt(typedValueParsed));

const route = await router.route(
  wethAmount,
  USDC,
  TradeType.EXACT_INPUT,
  {
    recipient: myAddress,
    slippageTolerance: new Percent(5, 100),
    deadline: Math.floor(Date.now()/1000 +1800)
  }
);

console.log(`Quote Exact In: ${route.quote.toFixed(2)}`);
console.log(`Gas Adjusted Quote In: ${route.quoteGasAdjusted.toFixed(2)}`);
console.log(`Gas Used USD: ${route.estimatedGasUsedUSD.toFixed(6)}`);

const transaction = {
  data: route.methodParameters.calldata,
  to: V3_SWAP_ROUTER_ADDRESS,
  value: BigNumber.from(route.methodParameters.value),
  from: MY_ADDRESS,
  gasPrice: BigNumber.from(route.gasPriceWei),
};

await web3Provider.sendTransaction(transaction);