Architecture & Code

📦 Interactive Contract Explorer

Click on any contract to expand and see its key functions. Uniswap V2 has just 3 core contracts — elegant simplicity.

🔄 Animated Transaction Flow

Follow a swap transaction as it travels from your wallet through the Router, Factory, and Pair contracts.

🔮 CREATE2 Address Derivation

Uniswap uses CREATE2 to compute pair addresses deterministically — no need to query the Factory. Enter two token addresses to see how it works.

// CREATE2 address derivation:
// pair = keccak256(0xff, factory, keccak256(tokenA, tokenB), initCodeHash)
//
// 1. Sort tokens: token0 < token1 (lexicographic)
// 2. salt = keccak256(abi.encodePacked(token0, token1))
// 3. address = keccak256(0xff ++ factory ++ salt ++ init_code_hash)[12:]
//
// This means anyone can compute the pair address offline!
// No need to call the Factory contract.

Factory:  0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f
Token A:  0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 (WETH)
Token B:  0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 (USDC)

→ Pair:   0xB4e16d0168e52d35CaCD2c6185b44281Ec28C9Dc (ETH/USDC)

⚡ Flash Swap Walkthrough

Flash swaps let you receive tokens before paying for them — as long as you pay back (with fee) in the same transaction. Powerful for arbitrage, liquidations, and collateral swaps.

// Example: Flash swap arbitrage
contract FlashArb {
    function execute(address pair, uint amount) external {
        // Step 1: Request tokens (triggers flash swap)
        IUniswapV2Pair(pair).swap(amount, 0, address(this), bytes("flash"));
    }

    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes data) external {
        // Step 4: We have the tokens! Do something profitable...
        uint profit = doArbitrage(amount0);

        // Step 5: Repay with fee
        uint fee = amount0 * 3 / 997 + 1;
        IERC20(token).transfer(msg.sender, amount0 + fee);
    }
}