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SiteCheck Web Intel JWT Token Inspector
x402
SiteCheck Web Intel JWT Token Inspector is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).
Decodes a JWT (header and payload) and reports its algorithm, key ID, claims, and time checks, flagging common security issues without verifying the signature
Price / call$0.002
Success—
StatusUnknown
How this service works
Decodes a JWT you supply (header and payload, base64url JSON) and reports its algorithm, key id, claims, and time checks (exp, nbf, iat). Flags alg none, symmetric HS algorithms, missing exp and a jku/x5u key reference. It does not verify the signature, because no key is given, and it does not fetch the key URL.
Output
Returns decoded JWT header fields (algorithm, type, key ID), payload claims (sub, iss, aud, exp, nbf, iat, and custom claims), time validity checks (expired, not-yet-valid, issued-at), and security flags for issues such as alg:none, symmetric HS algorithms, missing expiration, and presence of jku/x5u key URL references. Does not verify the signature.
Example use cases
Security audit of issued token
“I found this JWT in our app logs and want to know what algorithm it uses, what claims are in it, and whether it has an expiration set — can you inspect it and flag any red flags? Token: eyJhbGciOiJub25lIiwidHlwIjoiSldUIn0.eyJzdWIiOiJ1c2VyMTIzIiwiYWRtaW4iOnRydWV9.”
Checking token expiry before use
“Can you decode this JWT and tell me if it's expired or not yet valid based on the exp and nbf fields? eyJhbGciOiJSUzI1NiIsImtpZCI6ImFiYzEyMyJ9.eyJzdWIiOiJ1c2VyNDU2IiwiZXhwIjoxNjAwMDAwMDAwLCJuYmYiOjE1OTAwMDAwMDB9.signature”
Identifying dangerous JWT algorithm
“Please inspect this token and let me know if it's using a weak or dangerous algorithm like HS256 or alg:none, and whether there's a jku or x5u key reference I should be worried about: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiYWRtaW4ifQ.xyz”
Technical details
Endpoint
GEThttps://api.webintel-api.workers.dev/api/security/jwt-token-inspector?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to quickly decode and audit a JWT without access to the signing key — ideal for security reviews, debugging, or automated token scanning pipelines. Prefer this over full JWT verification libraries when you only need structural inspection, claim extraction, and common vulnerability flagging (alg:none, missing exp, weak algorithms) and don't need cryptographic signature validation.
Side effects
- Malformed or non-base64url token returns a parse error
- Token exceeding 8 KB limit is rejected
- Missing 'token' query parameter returns a validation error
- Tokens with encrypted payloads (JWE) cannot be decoded
- Network or worker availability issues may cause 5xx errors
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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