# JWT Decoder / JSON Web Token Inspector

> JWT Decoder / JSON Web Token Inspector is a paid API for AI agents from x402-deployer.x402-deployer.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).

Decodes and inspects JWT tokens by parsing header, payload, and standard claims without signature verification

## Facts

- Endpoint: POST https://x402-deployer.x402-deployer.workers.dev/jwt-decode
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-deployer-x402-deployer-workers-dev-dae356ee
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5UL3ifZD5Ae7kmXo94PTz

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 x402-deployer-x402-deployer-workers-dev-dae356ee -d '<json body>'
```

Example prompt: Can you decode this JWT for me and tell me who issued it, what the subject is, whether it's expired, and what algorithm it uses: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiaXNzIjoiYXV0aDAuY29tIiwiZXhwIjoxNjAwMDAwMDAwfQ.signature

## When to prefer this

Use this endpoint when you need to quickly inspect or debug the contents of a JWT token — extracting claims like issuer, subject, expiration, and algorithm — without needing to verify its cryptographic signature. Ideal for debugging Auth0, Cognito, Firebase, or generic OAuth tokens during development or troubleshooting.

## Known failure modes

- Malformed or non-JWT string returns a parse error
- Token with invalid Base64URL encoding fails to decode
- Missing required token field returns a 400-level error
- Expired token is still decoded but flagged as is_expired=true

## How this service works

JWT decoder / JWT parser / JSON Web Token inspector / Bearer token debugger / OAuth ID-token reader / Auth0 + Cognito + Firebase token inspector. Base64URL-decodes header and payload, parses standard claims (iss, aud, sub, exp, iat, nbf, jti), reports algorithm, key id (kid), token type (typ), TTL, and clock-validity (is_expired / is_not_yet_valid / is_currently_valid_by_clock). Does NOT verify signatures — for inspection only, never trust output for auth decisions.

## Output

Returns decoded JWT header fields (algorithm, kid, typ), payload with all standard claims (iss, aud, sub, exp, iat, nbf, jti), computed TTL in seconds, and clock-validity status flags (is_expired, is_not_yet_valid, is_currently_valid_by_clock). Does not verify the signature.

## Example request

```json
{
 "input": {
  "body": {
   "jwt": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c2VyMTIzIiwiaXNzIjoiZXhhbXBsZS5jb20iLCJleHAiOjk5OTk5OTk5OTksImlhdCI6MTYwMDAwMDAwMH0.test_signature"
  },
  "type": "http",
  "method": "POST",
  "bodyType": "json"
 }
}
```

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [
      "jwt"
     ],
     "properties": {
      "jwt": {
       "type": "string",
       "description": "Compact-serialization JWT string (three base64url segments separated by '.'). May be prefixed with 'Bearer ' — that prefix is stripped automatically."
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "note": {
       "type": "string"
      },
      "type": {
       "type": "null"
      },
      "claims": {
       "type": "object",
       "properties": {
        "jti": {
         "type": "null"
        },
        "issuer": {
         "type": "null"
        },
        "subject": {
         "type": "string"
        },
        "audience": {
         "type": "null"
        },
        "issued_at": {
         "type": "null"
        },
        "expires_at": {
         "type": "null"
        },
        "not_before": {
         "type": "null"
        },
        "ttl_seconds": {
         "type": "null"
        }
       }
      },
      "header": {
       "type": "object",
       "properties": {
        "alg": {
         "type": "string"
        }
       }
      },
      "key_id": {
       "type": "null"
      },
      "payload": {
       "type": "object",
       "properties": {
        "sub": {
         "type": "string"
        }
       }
      },
      "algorithm": {
       "type": "string"
      },
      "signature": {
       "type": "string"
      },
      "is_expired": {
       "type": "boolean"
      },
      "is_not_yet_valid": {
       "type": "boolean"
      },
      "payload_size_bytes": {
       "type": "integer"
      },
      "is_currently_valid_by_clock": {
       "type": "boolean"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-deployer-x402-deployer-workers-dev-dae356ee/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-deployer.x402-deployer.workers.dev](https://www.zero.xyz/host/x402-deployer.x402-deployer.workers.dev/llms.txt)