# PennyRail JWT Inspect

> PennyRail JWT Inspect is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Inspects and decodes a JWT token, returning its header, payload, and signature components

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/skill/jwt.toolkit--jwt-inspect
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-jwt-inspect-2dd92d12
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_K7QEk2z3P5sfNJc0z4Syi

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 pennyrail-jwt-inspect-2dd92d12 -d '<json body>'
```

Example prompt: Can you decode this JWT for me and show me what's in the payload and header? Here's the token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

## When to prefer this

Use this endpoint when you need to quickly inspect or decode a JWT token to read its claims, header algorithm, or expiry without needing cryptographic signature verification. Prefer this over a full JWT validation endpoint when you only need to read token contents, not confirm authenticity. Ideal for debugging auth flows, auditing token structure, or extracting identity claims in automated pipelines.

## Known failure modes

- Malformed or non-JWT input returns an error indicating the token could not be parsed
- Missing 'input' object in request body returns a validation error
- Truncated JWT with missing segments fails to decode
- Payment failure or missing x402 payment header results in 402 response
- Very large or deeply nested JWT payloads may time out

## How this service works

Machine-readable settlement service

## Output

Returns the decoded JWT broken into its three parts: the header (algorithm, token type), the payload (all claims such as sub, iss, exp, iat, and any custom claims), and metadata about the token structure. The signature is surfaced but not cryptographically verified against a secret.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-jwt-inspect-2dd92d12/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)