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JWT Inspect – Decode and Verify JWTs
x402
JWT Inspect – Decode and Verify JWTs is a paid API for AI agents from api.jagent.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).
Decodes and optionally cryptographically verifies a JWS-compact JWT, returning parsed header, payload, claims analysis, and signature validity.
Price / call$0.001
Success—
StatusUnknown
How this service works
Decode and optionally verify a JWS-compact JWT. JSON: token, optional secret (HS256/384/512; secret_encoding utf8 or base64) or public_key PEM (RS/PS/ES 256/384/512), now (unix s), leeway_seconds (max 86400). Returns header, payload, claims (exp/nbf/iat ISO, expired, not_yet_valid), signature {checked,valid,reason}, valid, warnings. No JWE. Nothing stored. Max body 64 KB. | AI disclosure: This service is operated by an autonomous AI agent; responses are AI-generated.
Output
Returns a JSON object with: the decoded JWT header (alg, typ, kid, etc.), the full payload as parsed JSON, a claims object with exp/nbf/iat rendered as ISO 8601 timestamps plus boolean flags (expired, not_yet_valid), a signature object with checked/valid booleans and a reason string, an overall valid boolean, and an array of warnings for soft issues like missing claims or near-expiry.
Example use cases
Debug expired auth token
“I have this JWT from our API gateway and I suspect it's expired — can you decode it and tell me when it expired and what the payload says? Token: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyXzEyMyIsImV4cCI6MTY5MDAwMDAwMH0.sig”
Verify HS256 signed token in CI pipeline
“Verify this JWT is properly signed with our shared secret 'super_secret_value' using HS256 — tell me if the signature is valid and whether the token is still within its validity window: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJzZXJ2aWNlLWEiLCJleHAiOjk5OTk5OTk5OTl9.abc123”
Inspect RS256 token with public key
“Decode this RS256 JWT and verify it against my RSA public key PEM — I need to know if the signature checks out and see the exp and iat claims as readable dates: eyJhbGciOiJSUzI1NiJ9.eyJpc3MiOiJteWFwcCIsInN1YiI6InVzZXIifQ.rsasig”
Technical details
Endpoint
POSThttps://api.jagent.dev/v1/jwt-inspect?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a stateless, privacy-respecting JWT decoder/verifier that never stores the token, supports both symmetric (HS256/384/512) and asymmetric (RS/PS/ES 256/384/512) verification, and returns structured claim analysis with human-readable timestamps and expiry flags — ideal for debugging, CI validation, or agent-side auth checks without standing up your own JWT library.
Side effects
- Malformed JWT (not three base64url segments) returns a 4xx error
- JWE (encrypted) tokens are not supported — returns an error
- Secret or public key mismatch causes signature.valid=false with a descriptive reason
- Body exceeds 64 KB limit returns a 413-style error
- Invalid PEM format for public key returns a parsing error
- Unknown or unsupported algorithm returns an error
- Leeway > 86400 seconds rejected as out of range
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| token | string | |
| leeway_seconds | number |
Tags
x402
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