# x402 Payment Preflight Checker

> x402 Payment Preflight Checker is a paid API for AI agents from anibalb.duckdns.org, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-31).

Checks whether a given HTTP endpoint is properly configured to accept x402 micropayments and returns a diagnostic verdict with payment details

## Facts

- Endpoint: GET https://anibalb.duckdns.org/x402/x402-payment-preflight?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-payment-preflight-checker-38ecb8f0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_tcjbVbCVo4nhf4KgSuFnN

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-payment-preflight-checker-38ecb8f0
```

Example prompt: Run an x402 payment preflight check using a GET method to see if that endpoint is properly configured to accept micropayments — I want to know the verdict, the score, and what payment address it expects.

## When to prefer this

Use this endpoint when you need to programmatically verify that an x402-gated API endpoint is correctly configured before attempting a micropayment — ideal for agent pre-flight logic, developer debugging, or automated compliance audits of x402 routes. Prefer this over manually inspecting 402 headers when you want a structured, scored diagnostic report.

## Known failure modes

- Target endpoint is unreachable or times out — checks array will reflect failed connectivity
- Endpoint does not return a 402 status — returns_402 check will fail and verdict will be non-payable
- Malformed payment header on target — payTo_checksum_ok will be false
- Invalid or unsupported HTTP method supplied — request rejected by schema validation
- Target endpoint is on an unsupported network — accepts array may be empty

## How this service works

Public data and utility APIs paid per call in USDC on Base (x402). No accounts, no API keys. 174 routes: crypto/equity data, onchain reads, DNS/email/security intel, geo/weather, x402 payment diagnostics, dev utilities and more.

## Output

Returns a JSON object with the target URL, a compliance score (0-100), an array of named diagnostic checks (each with pass/fail status), the HTTP status code received, accepted payment terms (amount, network, USD price, checksum validity), a boolean payability flag, and an overall verdict string (e.g. 'payable').

## 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",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://example.com/api",
  "score": 100,
  "checks": [
   {
    "ok": true,
    "name": "returns_402"
   }
  ],
  "status": 402,
  "accepts": [
   {
    "amount": "1000",
    "network": "eip155:8453",
    "price_usd": 0.001,
    "payTo_checksum_ok": true
   }
  ],
  "payable": true,
  "verdict": "payable"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-payment-preflight-checker-38ecb8f0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from anibalb.duckdns.org](https://www.zero.xyz/host/anibalb.duckdns.org/llms.txt)