Swap Signatures

MEVSwap uses signatures to let retail users swap tokens securely on Uniswap V4 pools. Signatures are required to protect against toxic orderflow (bots & market makers).

Get Started

1. Grab an API Key from Merkle Blockchain Services.

2. Request a Signature:

   {
     "chain_id": 1,
     "pool_id": "0x0000000000000000000000000000000000000000", // uniswap v4 pool id
     "sender": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48", // the signer of the swap transaction
     "zero_for_one": true,
     "amount_specified": "-1000000000000000000", // Negative for input, positive for output
     "deadline": "1600000000"
   }

   • Send a POST request to MEV Swap Service API: https://api.mevswap.com/v1/signature

   • Add your API key in the X-API-Key header.

   • Response:

   {
       "signature": "0xabcdef1234567890..."
   }

3. Build HookData:

   /// @notice Struct containing authorization data for hook
   struct HookData {
       // -------- FOR MEV AUCTIONS --------
       /// @notice nonce committed by MEV bot
       uint256 nonce; // use 0 for signature swaps
       // --------- FOR SWAPS --------
       /// @notice Signature authorizing the swap
       bytes signature;
       /// @notice deadline after which the signature is invalid
       uint256 deadline;
       /// @notice the swapper address
       address swapper;
   }

   Encode it:

   const hookData = ethers.utils.defaultAbiCoder.encode(
     ["uint256", "bytes", "uint256", "address"],
     [0, "0xabcdef1234567890...", 1600000000, "0xabcdef1234567890abcdef1234567890abcdef12"]
   );

4. Example: Swap with Universal Router:

   • Exact Input (e.g., 1 ETH → USDC):

     const commands = "0x10"; // Commands.V4_SWAP
     const inputs = [[
       ["SWAP_EXACT_IN_SINGLE", poolKey, true, "-1000000000000000000", "0", hookData],
       ["SETTLE_ALL", "ETH", "1000000000000000000"],
       ["TAKE_ALL", "USDC", "0"]
     ]];
     await universalRouter.execute(commands, inputs, deadline, { value: "1000000000000000000" });

   • Exact Output (e.g., USDC → 1 ETH):

     const commands = "0x10"; // Commands.V4_SWAP
     const inputs = [[
       ["SWAP_EXACT_OUT_SINGLE", poolKey, false, "1000000000000000000", "340282366920938463463374607431768211455", hookData],
       ["SETTLE_ALL", "USDC", "340282366920938463463374607431768211455"],
       ["TAKE_ALL", "ETH", "1000000000000000000"]
     ]];
     await universalRouter.execute(commands, inputs, deadline);