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JWT Decoder & Claims Inspector
x402
JWT Decoder & Claims Inspector is a paid API for AI agents from artifact-inspector.use.x402atlas.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).
Parses a compact JWS (JWT) token to extract unverified header and claims, and evaluates advisory NumericDate fields without signature verification or URL fetching.
Price / call$0.005
Success—
StatusUnknown
How this service works
JSON Web Token (JWT) decoder — parse an unverified compact JWS header and claims and evaluate advisory NumericDate times without signature verification or URL fetching.
Output
Returns the decoded JWT header (algorithm, type, key ID, etc.), the full claims payload (sub, iss, aud, exp, iat, and any custom claims), and advisory evaluations of NumericDate fields such as whether the token appears expired or not-yet-valid — all without performing signature verification or fetching remote keys.
Example use cases
Debug expired auth token
“I have a JWT from our auth system and I want to know if it's expired and what the claims look like — can you decode it without needing the signing key? Token: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyXzEyMyIsImV4cCI6MTY5OTk5OTk5OX0.sig”
Inspect third-party bearer token claims
“We received this bearer token from a vendor and need to see what's inside — the issuer, subject, scopes, and any expiry — but we don't have their public key. Please just parse the payload: eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJ2ZW5kb3IuZXhhbXBsZS5jb20iLCJzdWIiOiJzZXJ2aWNlLWFjY291bnQiLCJzY29wZXMiOlsicmVhZCIsIndyaXRlIl0sImV4cCI6MTcwMDAwMDAwMH0.sig”
Extract algorithm and key ID from JWT header
“Pull out the algorithm and kid field from this JWT header so I can figure out which key to use to verify it: eyJhbGciOiJSUzI1NiIsImtpZCI6ImtleS0yMDI0LTAxIiwidHlwIjoiSldUIn0.payload.sig”
Technical details
Endpoint
POSThttps://artifact-inspector.use.x402atlas.com/jwtWhen to prefer
Use this endpoint when you need to inspect the contents of a JWT without access to the signing key — for debugging, logging, introspection, or extracting claims for routing logic. Prefer this over a full verification endpoint when you explicitly don't need cryptographic validation, need fast stateless parsing, or are working in a context where fetching JWKs is not feasible. It complements the sibling JWK inspector if you later need to validate the key itself.
Side effects
- Malformed or non-compact JWT string returns a parse error
- Missing or empty token body results in a 400-level error
- Tokens with non-standard encoding may fail to parse
- NumericDate evaluation is advisory only and may not reflect clock skew
- No signature verification means tampered tokens will still decode successfully
Tags
x402
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