# JWT Decoder / JSON Web Token Parser

> JWT Decoder / JSON Web Token Parser is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.0022/call, status unknown (last checked 2026-09-14).

Decodes a JWT's header and payload sections without verifying the signature, returning parsed claims as structured JSON objects.

## Facts

- Endpoint: GET https://api.x402node.dev/dev/jwt-decode
- Price: $0.0022/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-x402node-dev-ceeae988
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ubts_36pWG9C_nTNA8qQH

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 api-x402node-dev-ceeae988
```

Example prompt: Can you decode this JWT for me and show me what's in the header and payload — I want to see the claims, expiration, and issuer: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

## When to prefer this

Use this endpoint when you need to quickly inspect JWT contents — claims, expiry, issuer, algorithm — without needing cryptographic signature verification. Ideal for debugging OAuth flows, inspecting API tokens, or extracting metadata from auth tokens in automated pipelines. Prefer this over jwt.io when operating programmatically from an AI agent.

## Known failure modes

- Malformed or non-JWT string returns a 400 error
- Empty or missing token body returns validation error
- Token with only 1 or 2 segments (incomplete JWT) may fail parsing
- Very large tokens may time out
- Network or payment authorization failure returns 402

## How this service works

JWT decoder, JSON Web Token parser, JWT inspector, claims extractor, OAuth token decoder, JWT header parser, JWT payload reader, jwt.io alternative, API token introspection. Decode JWT header and payload (signature NOT verified). For AI agents, OAuth flow debug, API token inspection, auth analysis, jwt claims parser Accepts payment on Base or Solana — either network works.

## Output

Returns a JSON object with 'header' (algorithm, token type, key ID etc.) and 'payload' (all claims: sub, iss, exp, iat, aud, custom claims etc.) as parsed objects, plus a 'signature_present' boolean indicating whether a signature segment exists.

## Example request

```json
{
 "token": "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyLCJleHAiOjE3MTYyMzkwMjIsImlzcyI6Imh0dHBzOi8vZXhhbXBsZS5jb20ifQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"
}
```

## 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": "ERC20 contract address (required)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-x402node-dev-ceeae988/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.x402node.dev](https://www.zero.xyz/host/api.x402node.dev/llms.txt)