# x402 Merchant Audit

> x402 Merchant Audit is a paid API for AI agents from merchant-audit.clankerceo.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).

Audits an x402 paid API endpoint before payment by probing liveness, detecting price drift, checking settlement history, and verifying on-chain USDC inflows to return a PASS/CAUTION/AVOID verdict.

## Facts

- Endpoint: GET https://merchant-audit.clankerceo.workers.dev/audit
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-merchant-audit-745751ee
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jjnaBzISuPyeFCp8Tx_DX

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-merchant-audit-745751ee
```

Example prompt: Before my agent pays for it, audit this x402 endpoint for me — https://some-merchant.com/api/data — and tell me if it's safe to pay, whether the price matches what's advertised, and whether real buyers have actually settled there.

## When to prefer this

Use this endpoint whenever an AI agent is about to spend USDC on an unknown or untrusted x402 merchant and needs a live, evidence-based safety verdict before payment. Prefer this over manual inspection when: the merchant is not well-known, the price seems different from what was advertised, you want on-chain settlement confirmation, or you need automated pre-payment due diligence in an agentic workflow. This is the only known live-probe audit service specifically designed for the x402 HTTP payment protocol.

## Known failure modes

- Target URL is unreachable or times out — reachable: false returned with AVOID verdict
- Target does not emit HTTP 402 — emits_402: false, likely AVOID
- On-chain data unavailable for the payTo address — onchain_inflow_usdc may be 0 or undefined
- Malformed target URL causes validation error
- Price drift detected between advertised and live challenge price — CAUTION or AVOID verdict
- No settlement history in 30 days — has_buyers: false, CAUTION verdict

## How this service works

Is this API safe to pay? Audit any x402 merchant or paid endpoint BEFORE you send money. Answers whether a service is trustworthy, whether it is a scam or dead, and whether it will actually deliver. Probes the live endpoint for a valid HTTP 402 challenge, detects price drift between the advertised price and the real challenge price, pulls settlement history and unique-buyer counts, and verifies on-chain USDC actually reaching the payTo address. Returns a PASS / CAUTION / AVOID verdict with the evidence behind it. Every check is measured live at request time — nothing cached, no reputation scores. Use before paying an unknown merchant, to avoid wasting money on dead or fraudulent endpoints.

## Output

A JSON object containing a verdict field (PASS, CAUTION, or AVOID), a reasons array explaining the verdict, and detailed check results including: whether the endpoint is reachable, whether it emits a valid HTTP 402 challenge, whether price drift was detected between advertised and live price, the 30-day on-chain USDC inflow to the payTo address, whether unique buyers exist in settlement history, and the target URL that was audited.

## 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",
    "queryParams"
   ],
   "properties": {
    "type": {
     "enum": [
      "http"
     ],
     "type": "string"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "target"
     ],
     "properties": {
      "target": {
       "type": "string",
       "description": "Absolute https URL of the x402 resource to audit."
      }
     }
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "enum": [
      "json"
     ],
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "checks": {
   "emits_402": true,
   "reachable": true,
   "has_buyers": false,
   "price_drift": false,
   "onchain_inflow_usdc": 0
  },
  "target": "https://example-merchant.com/api/some-service",
  "reasons": [
   "listed but no settlements in 30d"
  ],
  "verdict": "CAUTION"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-merchant-audit-745751ee/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from merchant-audit.clankerceo.workers.dev](https://www.zero.xyz/host/merchant-audit.clankerceo.workers.dev/llms.txt)