{"uid":"cap_b2cIv-5k5XEXpMaFnCstg","slug":"eip-712-typed-data-hash-calculator-89390ffc","name":"EIP-712 Typed Data Hash Calculator","description":"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","url":"https://api.x402node.dev/crypto/eip712-hash","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"types":{"type":"string","description":"Types object/JSON (required)"},"domain":{"type":"string","description":"EIP-712 domain object/JSON (required)"},"message":{"type":"string","description":"Message object/JSON (required)"},"primaryType":{"type":"string","description":"Primary type name (required)"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_sBY1fTZ5lxSviYjdMTW7i","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the exact EIP-712 typed-data hash, domain separator, and struct hash (keccak256 digest) used for Ethereum signature recovery","exampleAgentPrompt":"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.","exampleUseCases":null,"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T07:14:53.927Z","isFirstParty":false}