{"uid":"cap_w4daM7baL5pwT6WhJ5cEj","slug":"fastx402-lab-jwt-decoder-a7509926","name":"FastX402 Lab JWT Decoder","description":"146 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.","url":"https://fastx402.tools/jwt-decode?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$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":["token"],"properties":{"now":{"type":"string","description":"Optional: current time as unix seconds, for a reproducible answer"},"token":{"type":"string","description":"The JWT"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"header":{"type":"object","properties":{"alg":{"type":"string"},"typ":{"type":"string"}}},"expired":{"type":"boolean"},"payload":{"type":"object","properties":{"exp":{"type":"integer"},"iat":{"type":"integer"},"sub":{"type":"string"}}},"algorithm":{"type":"string"},"issued_at":{"type":"string"},"expires_at":{"type":"string"},"signature_present":{"type":"boolean"},"seconds_until_expiry":{"type":"integer"}}}}}}},"responseSchema":{"type":"json","example":{"header":{"alg":"HS256","typ":"JWT"},"expired":false,"payload":{"exp":1790003600,"iat":1790000000,"sub":"agent-42"},"algorithm":"HS256","issued_at":"2026-09-21T14:13:20Z","expires_at":"2026-09-21T15:13:20Z","signature_present":true,"seconds_until_expiry":1800}},"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_sgSlavmX4jmEvx-QGvQ0s","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":"Decodes a JWT's header and payload, reporting algorithm, issue/expiry times, expiration status, and seconds until expiry — without verifying the signature.","exampleAgentPrompt":"Can you decode this JWT for me and tell me whether it's expired, when it was issued, and what signing algorithm it uses? Token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyLTEyMyIsImlhdCI6MTc5MDAwMDAwMCwiZXhwIjoxNzkwMDAzNjAwfQ.abc123","exampleUseCases":[{"title":"Debugging expired auth token","prompt":"I'm getting a 401 error and I think my JWT might be expired — can you decode this token and tell me when it expires and whether it's still valid? eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJhZ2VudC00MiIsImlhdCI6MTc5MDAwMDAwMCwiZXhwIjoxNzkwMDAzNjAwfQ.signature"},{"title":"Checking JWT algorithm in use","prompt":"What signing algorithm is this JWT using? eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyLTEiLCJpYXQiOjE3OTAwMDAwMDAsImV4cCI6MTc5MDAwMzYwMH0.sig — I need to know if it's HS256 or RS256 before I update the auth middleware."},{"title":"Inspecting token lifetime during CI test","prompt":"During our integration test, decode this JWT and confirm it won't expire in the next 10 minutes: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ0ZXN0LXVzZXIiLCJpYXQiOjE3OTAwMDAwMDAsImV4cCI6MTc5MDA2MDAwMH0.testsig — use 1790000000 as the current time for a reproducible result."}],"resultDescription":"Returns a JSON object containing the decoded JWT header (alg, typ), the decoded payload (sub, iat, exp, plus any other claims), the algorithm string, human-readable issued_at and expires_at timestamps in ISO 8601, an expired boolean, whether a signature is present, and the number of seconds until expiry (negative if already expired).","failureModes":["Malformed or non-JWT string causes a parse error response","Missing required 'token' query parameter returns a validation error","Token with no expiry claim (no 'exp') may return null or zero for expiry-related fields","Network or payment failure returns a 402 or 5xx response"],"whenToPreferThis":"Choose this endpoint when you need to quickly inspect JWT claims, algorithm, or expiration status during debugging or automation — especially when signature verification is unnecessary or the secret/key is unavailable. It is ideal for lightweight token inspection in CI pipelines, agent auth flows, or log analysis. Prefer a full JWT verification library when you actually need cryptographic signature validation.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-17T12:38:24.461Z","isFirstParty":false,"canonicalSlug":"fastx402-lab-jwt-decoder-a7509926"}