# JWT Decoder API

> JWT Decoder API is a paid API for AI agents from jwt-decoder.api.klymax402.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-13).

Decodes a JWT token into its header and payload components without performing signature verification

## Facts

- Endpoint: GET https://jwt-decoder.api.klymax402.com/api/decode
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/jwt-decoder-api-2c73289e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4k91DbsnWMqarQaLNfvWb

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-api-2c73289e
```

Example prompt: Can you decode this JWT token for me and show me what's in the header and payload? eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.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 claims, checking expiration, or examining the header — without needing to cryptographically verify the signature. Ideal for debugging, logging, or extracting metadata from tokens when the signing secret is unavailable.

## Known failure modes

- Malformed JWT (not in header.payload.signature format) returns an error
- Missing token parameter returns a validation error
- Token with invalid base64url encoding in header or payload returns a parse error
- Empty string token returns an error

## How this service works

Decode a JWT token without signature verification

## Output

Returns the decoded JWT broken into its constituent parts: the header (containing algorithm and token type), the payload (containing claims such as subject, issuer, expiration, and any custom fields), and optionally the raw signature component. Note: no signature verification is performed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "token": {
   "type": "string",
   "description": "The JWT token to decode (format: header.payload.signature)"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/jwt-decoder-api-2c73289e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from jwt-decoder.api.klymax402.com](https://www.zero.xyz/host/jwt-decoder.api.klymax402.com/llms.txt)