# 402Check — x402 Endpoint Auditor

> 402Check — x402 Endpoint Auditor is a paid API for AI agents from agent-json-utility.pablovph.chatgpt.site, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Audits any x402 payment-gated endpoint for protocol compliance and agent-discovery readiness, returning a scored checklist of findings.

## Facts

- Endpoint: POST https://agent-json-utility.pablovph.chatgpt.site/v1/audit
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/402check-x402-endpoint-auditor-3eb37d89
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RdWSemry3DukWWhg0uOh7

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 402check-x402-endpoint-auditor-3eb37d89 -d '<json body>'
```

Example prompt: Can you audit my x402 endpoint at https://api.myservice.com/premium-data using a GET request and tell me whether it's protocol-ready and what its compliance score is?

## When to prefer this

Use this endpoint when you need to verify that an x402 payment-gated API is correctly implementing the protocol before listing it on a facilitator, debugging agent-discovery failures, or confirming a protocol version upgrade. It is purpose-built for x402 compliance and returns a structured per-check breakdown with a numeric score, making it more actionable than generic HTTP health checks or manual inspection.

## Known failure modes

- Target URL is unreachable or returns a non-402 status on first probe — audit fails with connectivity error
- Target endpoint does not implement x402 at all — all checks fail, score near zero
- Malformed or missing PaymentRequired header causes protocol-version check to fail
- POST endpoint audit without a body may return unexpected responses, leading to misleading check results
- Rate limiting or firewall on the target URL blocks the auditor probe

## How this service works

Audit any x402 payment endpoint for protocol and discovery compatibility.

## Output

Returns a JSON object with a boolean `ready` flag, an integer compliance `score` (0–100), an array of named checks each with a pass/fail status and explanatory message, and a plain-English `summary` of the audit findings and any hardening recommendations.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "description": "Public HTTPS x402 endpoint to audit"
  },
  "body": {
   "type": "object",
   "description": "Optional JSON body for a POST endpoint",
   "additionalProperties": true
  },
  "method": {
   "enum": [
    "GET",
    "POST"
   ],
   "type": "string",
   "default": "GET"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ready": true,
  "score": 92,
  "checks": [
   {
    "id": "status-402",
    "passed": true,
    "message": "Endpoint returns HTTP 402"
   },
   {
    "id": "protocol-v2",
    "passed": true,
    "message": "PaymentRequired uses x402 v2"
   }
  ],
  "summary": "Protocol-ready with one hardening recommendation."
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/402check-x402-endpoint-auditor-3eb37d89/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-json-utility.pablovph.chatgpt.site](https://www.zero.xyz/host/agent-json-utility.pablovph.chatgpt.site/llms.txt)