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EIP-712 Typed Data Hash Calculator
x402
EIP-712 Typed Data Hash Calculator is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).
Computes the exact EIP-712 typed-data hash, domain separator, and struct hash (keccak256 digest) used for Ethereum signature recovery
Price / call$0.005
Success—
StatusUnknown
How this service works
Compute the exact EIP-712 typed-data hash, domain separator and struct hash from domain, types, primaryType and message - the precise keccak256 digest used for signature recovery that LLMs cannot calculate. eip712 hash, typed data hash, eip-712, domain separator, struct hash, signature digest
Output
Returns the computed EIP-712 hash (keccak256 digest ready for signature recovery), the domain separator hash, and the struct hash — the exact same values an Ethereum wallet computes internally when signing typed data.
Example use cases
Example prompt
“Calculate the EIP-712 typed data hash for a permit signature — the domain is name 'MyToken', version '1', chainId 1, verifyingContract '0xAbC...', the primaryType is 'Permit', the types include Permit with fields owner, spender, value, nonce, deadline as address/address/uint256/uint256/uint256, and the message has owner '0x123...', spender '0x456...', value 1000000, nonce 0, deadline 1700000000 — I need the exact keccak256 digest, domain separator, and struct hash.”
Technical details
Endpoint
POSThttps://api.x402node.dev/crypto/eip712-hashWhen to prefer
Use this endpoint when you need the precise EIP-712 keccak256 digest that an Ethereum wallet or smart contract would compute — especially critical when LLMs cannot reliably perform keccak256 arithmetic, when verifying signatures off-chain, when debugging EIP-712 signing flows, or when building permit/meta-transaction tooling that requires the exact domain separator and struct hash.
Side effects
- Malformed or missing domain fields return a 400 error
- Invalid or inconsistent types definition causes a hash computation failure
- primaryType not found in types object returns an error
- Mismatched message fields vs declared types produce an error
- Network or payment authorization failure returns a 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| types | string | Types object/JSON (required) |
| domain | string | EIP-712 domain object/JSON (required) |
| message | string | Message object/JSON (required) |
| primaryType | string | Primary type name (required) |
Tags
x402
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