{"uid":"cap_CFc4H47S8_5P_SGt34m-u","slug":"agent402-tools-hmac-signature-06af5b8d","name":"agent402.tools HMAC Signature","description":"HMAC signature of a message with a shared key. Algorithms: sha256 (default), sha512, sha1. Returns hex and base64.","url":"https://agent402.tools/api/hmac","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"key":{"type":"string","description":"Shared secret key"},"algo":{"type":"string","description":"sha256 | sha512 | sha1"},"text":{"type":"string","description":"Message to sign (max 100KB)"}}},"responseSchema":{"type":"json","example":{"hex":"f7bc…","algo":"sha256","base64":"97w…"}},"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_BdBl0bR8Y662vm5cATYX8","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 an HMAC signature of a message using a shared secret key, returning both hex and base64 encodings, with support for SHA-256, SHA-512, and SHA-1 algorithms.","exampleAgentPrompt":"Compute an HMAC-SHA256 signature for the message 'order_id=12345&amount=99.99' using the shared secret key 'mysecretkey123' and give me both the hex and base64 outputs.","exampleUseCases":null,"resultDescription":"Returns an HMAC signature of the provided message in both hexadecimal and base64 formats, computed using the specified algorithm (sha256, sha512, or sha1) and the shared secret key.","failureModes":["Missing required fields (key or text) returns a 400 error","Message exceeds 100KB limit returns a payload too large error","Invalid algorithm value (not sha256, sha512, or sha1) returns a validation error","Payment failure returns a 402 Payment Required response"],"whenToPreferThis":"Use this endpoint when you need a quick, pay-per-use HMAC signature computation without setting up a local crypto library, especially useful in agent workflows needing message authentication or webhook signature generation. Prefer this over building custom crypto logic when operating in environments without native crypto support.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T19:14:04.891Z","isFirstParty":false}