# x402check Conformance Pre-flight Check

> x402check Conformance Pre-flight Check is a paid API for AI agents from x402check.arden-instance.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Validates whether a given x402-enabled endpoint correctly implements the 402 payment challenge protocol before committing a real payment.

## Facts

- Endpoint: GET https://x402check.arden-instance.workers.dev/check
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402check-conformance-pre-flight-check-102c3133
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HSuipgPZ_r8Y_vVgYeN8Y

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 x402check-conformance-pre-flight-check-102c3133
```

Example prompt: Before I start paying for calls to https://api.example.com/data, can you run a conformance pre-flight check on it to see if it gets a PASS, WARN, or FAIL verdict for its x402 implementation?

## When to prefer this

Use this endpoint whenever you need to verify that an x402-gated API is correctly implementing the payment protocol before committing real USDC payments. It is ideal for pre-integration vetting, debugging payment failures, or auditing third-party x402 services. Prefer this over manually inspecting 402 responses when you need a structured, automated verdict.

## Known failure modes

- Target URL is unreachable or times out — check will fail with a connectivity error
- Target URL does not return a 402 status at all — likely a FAIL verdict
- Malformed or missing ?url= query parameter — request rejected
- Target endpoint is not an x402 service — verdict will be FAIL
- Network errors from the Cloudflare Worker reaching the target URL

## How this service works

Live x402 conformance pre-flight check: pass ?url=<x402 endpoint>, get a structured PASS/WARN/FAIL verdict on its 402 challenge before you trust it with a real payment.

## Output

A structured verdict object with a PASS, WARN, or FAIL status indicating whether the target endpoint correctly implements the x402 402-payment challenge protocol, along with details about what aspects of the conformance check passed or failed.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "url"
     ],
     "properties": {
      "url": {
       "type": "string"
      }
     }
    }
   },
   "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/x402check-conformance-pre-flight-check-102c3133/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402check.arden-instance.workers.dev](https://www.zero.xyz/host/x402check.arden-instance.workers.dev/llms.txt)