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EIP-712 Typed Data Builder & Signer Recovery
x402
EIP-712 Typed Data Builder & Signer Recovery is a paid API for AI agents from x402-audit.tatschluizguilherme.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).
Computes EIP-712 domainSeparator, hashStruct, and final digest from typed data, and optionally recovers the signer address via ecrecover — all offline with no RPC or API key
Price / call$0.1
Success—
StatusUnknown
How this service works
Pay-per-call on-chain API for AI agents and developers: wallet audits, token safety audits (honeypot detection), live gas prices, token prices, transaction receipts, balances, ENS resolution, block data, ERC-20 allowances, transaction simulation, swap quotes and multicall batches — all computed on-chain via public RPCs (no external market API). Pay per request in USDC on Base via the x402 exact scheme (EIP-3009 transferWithAuthorization). No API key, no signup, no subscription.
Output
Returns normalized typed data, the computed domainSeparator (32-byte hex), hashStruct (32-byte hex), and the final EIP-712 digest (32-byte hex). If a signature was provided, also returns the recovered signer address (ecrecover result) and a recover.ok boolean indicating whether it matches the optional expectedAddress.
Example use cases
Verify off-chain Permit signature
“I have an EIP-712 Permit signature from a user claiming to have signed a token approval — here's the domain, types, message JSON, and a 65-byte signature starting with 0x. Can you recover the signer address and tell me if it matches 0x1234...abcd?”
Build Permit2 digest for relayer
“I'm building a relayer and need the exact 32-byte digest that the wallet will sign for a Permit2 transfer. Here's my domain (name: Permit2, chainId: 8453, verifyingContract: 0x000000000022D473030F116dDEE9F6B43aC78BA3), the nested PermitTransferFrom types, and the message — give me the domainSeparator, hashStruct, and final digest.”
Debug off-chain governance vote
“My off-chain voting contract uses EIP-712 structured data. Can you normalize my Vote struct (domain, types, primaryType, and message JSON attached), show me the domainSeparator and hashStruct, and verify that the 65-byte signature I got actually came from voter address 0xDEAD...BEEF?”
Technical details
Endpoint
GEThttps://x402-audit.tatschluizguilherme.workers.dev/eip712When to prefer
Choose this endpoint when you need pure offline EIP-712 cryptography — building digests, checking domainSeparators, or verifying signers — without any RPC call, blockchain connection, or API key. Ideal for relayers, Permit/Permit2 flows, off-chain vote verification, and debugging typed data that a wallet will sign. Prefer over on-chain alternatives when speed, privacy, and zero infrastructure dependency matter.
Side effects
- Malformed domain or types JSON returns a 400-level error with a description of the parsing failure
- Invalid signature format (not 0x + 65 bytes) causes ecrecover to fail or return an error
- Mismatched expectedAddress results in recover.ok: false rather than an error
- Unsupported uintN size or invalid address format may produce a normalization error
- Deeply nested or circular struct definitions may cause a processing error
Output
Schema · Response
{
"type": "json",
"example": {
"types": {
"Permit": [
{
"name": "owner",
"type": "address"
},
{
"name": "spender",
"type": "address"
},
{
"name": "value",
"type": "uint256"
},
{
"name": "nonce",
"type": "uint256"
},
{
"name": "deadline",
"type": "uint256"
}
],
"EIP712Domain": [
{
"name": "name",
"type": "string"
},
{
"name": "version",
"type": "string"
},
{
"name": "chainId",
"type": "uint256"
},
{
"name": "verifyingContract",
"type": "address"
}
]
},
"digest": "0x5c2f3e4d5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e",
"domain": {
"name": "USDC",
"chainId": "8453",
"version": "2",
"verifyingContract": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913"
},
"message": {
"nonce": "0",
"owner": "0xd8da6bf26964af9d7eed9e03e53415d37aa96045",
"value": "1000000",
"spender": "0x1111111111111111111111111111111111111111",
"deadline": "1900000000"
},
"network": "offline",
"hashStruct": "0x8b3d9f2a1c4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b",
"primaryType": "Permit",
"requestedAt": "2026-08-05T09:00:00.000Z",
"domainSeparator": "0x8a8268fd2a7b6f2c8ab62e4b0c2c2c9f4c3e2f1a0b9c8d7e6f5a4b3c2d1e0f1a2"
}
}Tags
x402
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