# JWT Decoder (dt0ur.online)

> JWT Decoder (dt0ur.online) is a paid API for AI agents from dt0ur.online, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-03).

Decodes a JWT's header and payload into readable JSON for inspection and debugging, without verifying the signature.

## Facts

- Endpoint: POST https://dt0ur.online/api/utility/jwt-decode?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-03
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/jwt-decoder-dt0ur-online-cd38fe43
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o1fs6wIlQxyNSorTMGgj-

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability jwt-decoder-dt0ur-online-cd38fe43 -d '<json body>'
```

Example prompt: Can you decode this JWT for me so I can see what claims are in the payload? Here's the token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

## When to prefer this

Use this endpoint when you need to quickly inspect or debug the contents of a JWT token — for example, to check expiry, read user claims, or audit the signing algorithm — without needing to validate its cryptographic signature. Prefer this over manual base64 decoding when you need a clean structured JSON output. Do NOT use this when you need to verify that a token is authentic or untampered; this endpoint provides no signature validation.

## Known failure modes

- Malformed JWT (not in three-part header.payload.signature format) returns an error
- Non-base64url-encoded segments cause a parsing failure
- Empty or missing token field returns a validation error
- Extremely large tokens may be rejected
- If the payload is not valid JSON after decoding, the result may be a raw string or error

## How this service works

Decodes a JWT's header and payload for inspection. Does NOT verify the signature — for debugging/inspection only, never trust the output as authenticated.

## Output

Returns the decoded JWT header (as a JSON object with fields like 'alg' and 'typ') and the decoded payload (as a JSON object with all encoded claims such as 'sub', 'iat', 'exp', 'roles', etc.). The signature is NOT verified — results should be treated as informational/debugging data only, not as authenticated.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "token": {
   "type": "string",
   "description": "A JWT in header.payload.signature form"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/jwt-decoder-dt0ur-online-cd38fe43/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dt0ur.online](https://www.zero.xyz/host/dt0ur.online/llms.txt)