# Quartermaster JWT Decoder

> Quartermaster JWT Decoder is a paid API for AI agents from quartermaster.surewhynot.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Decodes a JWT token's header and payload into readable JSON without verifying the signature.

## Facts

- Endpoint: GET https://quartermaster.surewhynot.app/v1/jwt-decode
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quartermaster-jwt-decoder-b06c9542
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_e4iHZZ471fH5RJwNrr2Dd

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 quartermaster-jwt-decoder-b06c9542
```

Example prompt: Can you decode this JWT for me and show me what's in the header and payload — I don't need signature verification, just want to read the claims: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

## When to prefer this

Use this endpoint when you need to quickly inspect the contents of a JWT token — such as reading expiration time, subject, issuer, or custom claims — without needing to verify its cryptographic signature. Ideal for debugging, logging, or extracting metadata from tokens where trust verification is handled separately.

## Known failure modes

- Malformed or non-JWT string returns an error indicating invalid token format
- Missing 'token' query parameter returns a validation error
- Token with fewer than 3 segments (not a valid JWT structure) fails to decode
- Extremely long tokens may be rejected

## How this service works

Decode a JWT header and payload (signature not verified).

## Output

Returns the decoded JWT header and payload as structured JSON objects, exposing all claims such as sub, iat, exp, iss, and any custom fields. Signature is NOT verified.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "token"
     ],
     "properties": {
      "token": {
       "type": "string",
       "description": "JWT to decode (signature NOT verified)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quartermaster-jwt-decoder-b06c9542/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from quartermaster.surewhynot.app](https://www.zero.xyz/host/quartermaster.surewhynot.app/llms.txt)