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x402 Utils – JWT Decoder
x402
x402 Utils – JWT Decoder is a paid API for AI agents from utils.kagurazaka.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-29).
Decodes a JWT's header and claims, returning the algorithm, payload, expiry timestamp, and whether the token has already expired — without verifying the signature.
Price / call$0.001
Success—
StatusUnknown
How this service works
Decode a JSON Web Token's header and claims, and say when it was issued, when it expires, whether it has expired and in how many seconds it will. The signature is not verified.
Output
A JSON object containing the JWT's algorithm (e.g. HS256), the full decoded payload as a key-value map of claims, the expiration timestamp as a UTC ISO 8601 string, a boolean indicating whether the token is expired, and the number of seconds until expiry (negative if already expired).
Example use cases
Debug expired auth token
“I'm getting a 401 on my API calls — can you decode this JWT and tell me if it's expired and when it was issued? eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyXzQ1NiIsImV4cCI6MTY5MDAwMDAwMH0.sig”
Inspect token claims for troubleshooting
“Can you decode this JWT and show me all the payload claims, the algorithm used, and exactly when it expires? eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyX2lkIjoiYWJjMTIzIiwicm9sZSI6ImFkbWluIiwiZXhwIjoxNzkyODg2NDAwfQ.sig”
Check token lifetime in automation pipeline
“Here's a JWT from our system — how many seconds until it expires, and has it already expired? eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJzdmNfYWNjb3VudCIsImV4cCI6MTc5MzAwMDAwMH0.sig”
Technical details
Endpoint
POSThttps://utils.kagurazaka.dev/v1/jwt?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to quickly inspect a JWT's contents, check its expiration, or extract claims without setting up a local JWT library. Ideal for debugging, automation pipelines, or when the signing secret is unavailable. Note: this does NOT verify the signature, so do not use it as a security gate — only for informational inspection.
Side effects
- Malformed or non-JWT string returns a parse error
- Token with no 'exp' claim may omit expiration fields
- Signature is never verified — a tampered token will still decode successfully
- Missing 'token' field in the request body returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| token | string | the JWT |
Output
Schema · Response
{
"type": "json",
"example": {
"expired": false,
"payload": {
"exp": 1792886400,
"sub": "123"
},
"algorithm": "HS256",
"expires_at": "2026-10-25T00:00:00.000Z"
}
}Tags
x402
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