# SiteCheck Web Intel JWT Token Inspector

> SiteCheck Web Intel JWT Token Inspector is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).

Decodes a JWT (header and payload) and reports its algorithm, key ID, claims, and time checks, flagging common security issues without verifying the signature

## Facts

- Endpoint: GET https://api.webintel-api.workers.dev/api/security/jwt-token-inspector?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-web-intel-jwt-token-inspector-63204513
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_b-oHYG_QrLSV9osgCgVfe

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 sitecheck-web-intel-jwt-token-inspector-63204513
```

Example prompt: Can you decode this JWT for me and flag any security issues like alg:none, missing expiration, or symmetric algorithms? Here's the token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

## When to prefer this

Use this endpoint when you need to quickly decode and audit a JWT without access to the signing key — ideal for security reviews, debugging, or automated token scanning pipelines. Prefer this over full JWT verification libraries when you only need structural inspection, claim extraction, and common vulnerability flagging (alg:none, missing exp, weak algorithms) and don't need cryptographic signature validation.

## Known failure modes

- Malformed or non-base64url token returns a parse error
- Token exceeding 8 KB limit is rejected
- Missing 'token' query parameter returns a validation error
- Tokens with encrypted payloads (JWE) cannot be decoded
- Network or worker availability issues may cause 5xx errors

## How this service works

Decodes a JWT you supply (header and payload, base64url JSON) and reports its algorithm, key id, claims, and time checks (exp, nbf, iat). Flags alg none, symmetric HS algorithms, missing exp and a jku/x5u key reference. It does not verify the signature, because no key is given, and it does not fetch the key URL.

## Output

Returns decoded JWT header fields (algorithm, type, key ID), payload claims (sub, iss, aud, exp, nbf, iat, and custom claims), time validity checks (expired, not-yet-valid, issued-at), and security flags for issues such as alg:none, symmetric HS algorithms, missing expiration, and presence of jku/x5u key URL references. Does not verify the signature.

## 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": "A JWT in compact form: header.payload.signature (required, max 8 KB)"
      }
     }
    }
   },
   "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/sitecheck-web-intel-jwt-token-inspector-63204513/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.webintel-api.workers.dev](https://www.zero.xyz/host/api.webintel-api.workers.dev/llms.txt)