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Agent402 UK — EIP-712 Typed Data Hash
x402
Agent402 UK — EIP-712 Typed Data Hash is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).
Computes the canonical EIP-712 typed data hash for a given domain, types, and message without consuming LLM tokens
Price / call$0.001
Success—
StatusDown
How this service works
Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.
Output
Returns a JSON object with a 'hash' field (a 0x-prefixed 32-byte hex string representing the canonical EIP-712 typed data hash) and a 'valid' boolean indicating whether the input was well-formed and the hash was successfully computed.
Example use cases
USDC permit hash before signing
“Hash this EIP-712 typed data for a USDC permit on Base: domain name is 'USD Coin', chainId 8453, verifyingContract is the Base USDC address, primaryType is 'Permit', and the message has owner, spender, value, nonce, and deadline fields filled in — give me the hex hash I need to sign.”
Smart contract meta-transaction signing
“I need the EIP-712 hash for a meta-transaction: domain is {name:'Forwarder',version:'1',chainId:8453}, primaryType 'ForwardRequest' with fields from, to, value, gas, nonce, and data — here's the full message object. What's the canonical hash?”
Off-chain order hash for DEX
“Compute the EIP-712 hash for a limit order typed data: the domain is my DEX contract on Base (chainId 8453), primaryType is 'Order' with fields maker, taker, tokenIn, tokenOut, amountIn, amountOut, expiry, and nonce. Here's the full message — I need the hash to confirm it matches what the contract will compute.”
Technical details
Endpoint
POSThttps://agent402.co.uk/v1/chain/eip712-hashWhen to prefer
Use this endpoint when you need a deterministic, token-free computation of an EIP-712 typed data hash — especially before signing USDC permits, meta-transactions, or any EVM structured data. Prefer this over having an LLM compute the hash inline (error-prone and expensive) or spinning up a local ethers.js/web3 environment. Ideal for agent pipelines that need to verify or pre-compute signatures on Base or other EVM chains without running code locally.
Side effects
- Malformed or missing 'types' object returns an error or valid:false
- Missing primaryType field causes hash computation to fail
- Domain fields that don't match EIP-712 spec may produce incorrect hashes without explicit error
- Mismatched message fields vs declared types may result in invalid:true
- Network or payment (x402) errors may return 402 Payment Required if USDC payment fails
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| types | object | Primary + referenced types (EIP712Domain optional) |
| domain | object | EIP-712 domain |
| message | object | Message matching primaryType |
| typedData | object | Optional envelope {domain,types,primaryType,message} |
| primaryType | string | Root type name |
Output
Schema · Response
{
"type": "json",
"example": {
"hash": "0xbe609aee343fb3c4b28e1df9e632fca64fcfaede20f02e86244efddf30957bd2",
"valid": true
}
}Tags
x402
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