{"uid":"cap_48hsIOxvFDdY03LQX_pa5","slug":"keccak256-hash-ethereum-function-selector-calculator-ccee6dad","name":"Keccak256 Hash & Ethereum Function Selector Calculator","description":"Compute the exact keccak256 hash and 4-byte function selector of any string or hex input - the precise Ethereum hash that LLMs cannot calculate correctly. keccak256, keccak hash, function selector, solidity hash, ethereum hash, 4byte selector","url":"https://api.x402node.dev/crypto/keccak","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"data":{"type":"string","description":"Data (optional)"},"text":{"type":"string","description":"String or 0x-hex to hash (required, max 100KB)"},"input":{"type":"string","description":"Input (optional)"}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.004","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":"$0.004/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_7Hn04HmqrbMGScnzKH0AJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.004","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the exact keccak256 hash and 4-byte function selector for any string or hex input, as used in Ethereum/Solidity smart contracts","exampleAgentPrompt":"What's the exact keccak256 hash and 4-byte function selector for the Solidity function signature 'transfer(address,uint256)'?","exampleUseCases":null,"resultDescription":"Returns the full keccak256 hash (32 bytes, hex-encoded) and the first 4 bytes as the Ethereum ABI function selector for the given input string or hex data","failureModes":["Invalid or malformed input returns an error response","Empty input may return a hash of empty string (edge case to handle carefully)","Non-hex input passed as hex may cause parsing errors","Network or payment authorization failure returns 402 or 5xx"],"whenToPreferThis":"Use this endpoint when you need a provably correct keccak256 hash or Ethereum function selector — LLMs cannot compute keccak256 accurately from first principles, so any time a smart contract interaction, ABI encoding, event topic, or Solidity hash is needed, this API provides the correct cryptographic result","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T13:07:50.775Z","isFirstParty":false}