{"uid":"cap_SWda7EfhQ-zIKFa4R2QS3","slug":"fastx402-lab-keccak256-hasher-a20bc6a3","name":"FastX402 Lab Keccak256 Hasher","description":"FastX402 Lab: small pay-per-call tools for AI agents, paid per request in USDC on Base over x402. No signup, no API key.","url":"https://lab.fastx402.tools/keccak256?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":[],"properties":{"hex":{"type":"string","description":"Hex bytes to hash, like 0x68656c6c6f; \"0x\" is empty"},"text":{"type":"string","description":"UTF-8 text to hash"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"hash":{"type":"string"},"input_bytes":{"type":"integer"}}}}}}},"responseSchema":{"type":"json","example":{"hash":"0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8","input_bytes":5}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_qaLkmZdQ8QVL-cFBqTaSd","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the Keccak-256 hash of a given hex byte string or UTF-8 text, paid per call in USDC over x402","exampleAgentPrompt":"Can you compute the Keccak-256 hash of the UTF-8 text 'hello world'?","exampleUseCases":[{"title":"Hash Ethereum function selector","prompt":"I need the Keccak-256 hash of the UTF-8 string 'transfer(address,uint256)' so I can get the 4-byte function selector for a Solidity call."},{"title":"Verify smart contract storage slot","prompt":"Hash the hex bytes 0x000000000000000000000000abcdef1234567890abcdef1234567890abcdef12 with keccak256 — I need to check what storage slot that maps to in my contract."},{"title":"Hash arbitrary data for signing","prompt":"Compute the keccak256 hash of the text 'Please sign this message to confirm your identity' so I can use it as the message digest for an Ethereum signature."}],"resultDescription":"Returns a JSON object with 'hash' (the 0x-prefixed 32-byte Keccak-256 digest as a hex string) and 'input_bytes' (the number of bytes that were hashed). Example: {\"hash\":\"0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8\",\"input_bytes\":5}.","failureModes":["Missing both 'hex' and 'text' query params — endpoint may return an error or hash empty input","Invalid hex string format (e.g. odd-length or non-hex chars) — returns error","Payment failure or insufficient USDC balance — returns HTTP 402 and no hash","Network timeout on the Base chain payment — request fails before hashing occurs"],"whenToPreferThis":"Choose this endpoint when you need a quick, no-signup Keccak-256 hash computation (for Ethereum/EVM use cases) and can pay $0.001 USDC per call via x402. Prefer it over running a local library when your agent environment lacks crypto libraries, or when you want a simple pay-as-you-go API with no key management. Not suitable if you need SHA-256 or other hash functions, or if you require batch hashing of many inputs cost-effectively.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-17T12:39:31.863Z","isFirstParty":false,"canonicalSlug":"fastx402-lab-keccak256-hasher-a20bc6a3"}