Trading Overview

Uniswap offers distinct methods for integrating swapping functionality into your application. Choosing the right approach depends on your specific needs regarding customization, control, and development resources.

Custom Linking (Simplest)

For applications that want to provide swapping capabilities without managing transactions, quoting, or a custom UI, you can link directly to the Uniswap interface using URL query parameters. This allows you to pre-fill the input/output tokens, the amount, and even the UI theme. Get started with all custom linking parameters.

How it works By appending specific parameters to https://app.uniswap.org/#/swap, the Uniswap frontend will automatically configure the swap interface for the user.

Example Usage To link to a swap of 10 units of a specific token as the input, you would use: https://app.uniswap.org/#/swap?field=input&value=10&inputCurrency=0x0F5D2fB29fb7d3CFeE444a200298f468908cC942

The Uniswap API (Easiest)

The Uniswap API provides a straightforward path to integration. It abstracts away the complexity of finding the most efficient route based on current inputs (splitting and hopping between Uniswap v2, v3, v4, and UniswapX) and constructing transaction calldata. Your app still handles signing and onchain submission. Get started with the API.

How it works

1. Check Approval: Use /check_approval to see if the user has authorized Permit2 or the router.
2. Get quote: Send a /quote request. The API returns routing and quote data.
3. Get Transaction: Send a /swap request. The API returns encoded transaction data
4. Submit: The user signs the returned transaction, and your app submits it onchain through your signer or RPC provider.

What you handle

You do not need to compile Solidity or manage pool state. You work with JSON responses, wallet signing, and transaction submission.

{
  "requestId": "<string>",
  "quote": {
    "orderInfo": {
      "chainId": 1,
      "input": {
        "startAmount": "1000000",
        "endAmount": "0",
        "token": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
      },
      "outputs": [
        {
          "startAmount": "0",
          "endAmount": "1000000",
          "token": "0xdAC17F958D2ee523a2206206994597C13D831ec7",
          "recipient": "0x123..."
        }
      ]
    }
  }
}

The Uniswap SDK (Flexible)

If you need offline computation, custom routing logic, or cannot rely on a hosted service, the TypeScript SDK is the standard client-side solution. The SDK provides utility classes for constructing pool keys, computing quotes, and encoding swap parameters, but it does not execute trades. You use the SDK's output to build transactions that you submit via a library like Ethers.js or Viem. Get started with the SDK.

How it works

To propose a trade using the Uniswap v4 SDK, you construct a PoolKey that identifies the pool, then call the onchain Quoter contract to simulate the swap and get an expected output amount. The Quoter uses state-changing calls designed to be reverted, so quotes must be fetched offchain using callStatic.

What you handle

You manage RPC connections, token definitions, and pool configuration. The SDK helps you structure all of this correctly.

import { ethers, parseUnits, formatUnits } from 'ethers'
import { Token, ChainId } from '@uniswap/sdk-core'

// Define tokens
const ETH_TOKEN = new Token(ChainId.MAINNET, '0x0000000000000000000000000000000000000000', 18, 'ETH')
const USDC_TOKEN = new Token(ChainId.MAINNET, '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48', 6, 'USDC')

// Construct the PoolKey identifying the V4 pool
const poolKey = {
  currency0: ETH_TOKEN.address,
  currency1: USDC_TOKEN.address,
  fee: 500,
  tickSpacing: 10,
  hooks: '0x0000000000000000000000000000000000000000',
}

// Reference the V4 Quoter contract
const quoterContract = new ethers.Contract(QUOTER_ADDRESS, QUOTER_ABI, provider)

// Simulate the swap off-chain to get a quote
const result = await quoterContract.callStatic.quoteExactInputSingle({
  poolKey: poolKey,
  zeroForOne: true,
  exactAmount: parseUnits('1', ETH_TOKEN.decimals).toString(),
  hookData: '0x00',
})

console.log(`Expected output: ${formatUnits(result.amountOut, USDC_TOKEN.decimals)} USDC`)

Smart Contracts (Native)

Building directly against the Uniswap v4 smart contracts gives you maximum control and composability. There are two distinct build paths depending on your goal:

Path A: Executing Swaps

If your goal is to perform swaps from an onchain contract, for example, as part of an arbitrage bot, a vault strategy, or a DeFi protocol that needs to swap tokens during its operations, you interact with the Universal Router or the PoolManager directly. Get started with smart contracts.

The Universal Router is the recommended entry point. It uses a command-encoding pattern where you pack a sequence of actions (swap, settle input tokens, take output tokens) into byte arrays and execute them in a single transaction.

// Encode the command: we want a V4 swap
bytes memory commands = abi.encodePacked(uint8(Commands.V4_SWAP));

// Encode the action sequence: swap → settle input → take output
bytes memory actions = abi.encodePacked(
    uint8(Actions.SWAP_EXACT_IN_SINGLE),
    uint8(Actions.SETTLE_ALL),
    uint8(Actions.TAKE_ALL)
);

// Encode parameters for each action
bytes[] memory params = new bytes[](3);
params[0] = abi.encode(
    IV4Router.ExactInputSingleParams({
        poolKey: key,
        zeroForOne: true,
        amountIn: amountIn,
        amountOutMinimum: minAmountOut,
        hookData: bytes("")
    })
);
params[1] = abi.encode(key.currency0, amountIn);      // settle
params[2] = abi.encode(key.currency1, minAmountOut);   // take

inputs[0] = abi.encode(actions, params);
router.execute(commands, inputs, deadline);

Safety Note: When trading from smart contracts, you must enforce slippage limits via amountOutMinimum or use an onchain price oracle. Setting this to zero makes your contract vulnerable to sandwich attacks and price manipulation.

Path B: Customizing Swaps with Hooks

If your goal is to extend or modify swap behavior itself, for example, to implement dynamic fees, on-swap oracles, limit orders, or access control, you write a hook contract. Get started with hooks.

Hooks are external contracts that a Uniswap v4 pool calls at specific points during its lifecycle. For swaps, two hook functions are available:

• beforeSwap: called before the swap executes. Can modify fees, enforce conditions, or reject the swap entirely.
• afterSwap: called after the swap executes. Receives the resulting BalanceDelta and can perform follow-up logic.

A hook contract declares which lifecycle points it implements via getHookPermissions(), and is associated with a pool during deployment.

FAQ