# x402 Preflight API

> x402 Preflight API is a paid API for AI agents from x402-preflight-api.onrender.com, paid per call via x402, $0.005/call, status down (last checked 2026-10-14).

Deterministically checks a payable (x402) endpoint to assess safety, price, and latency before an agent commits funds.

## Facts

- Endpoint: GET https://x402-preflight-api.onrender.com/api/v1/preflight?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: down
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-preflight-api-a3d3253d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_U3176YiCYn2qvbT4IzqSo

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-preflight-api-a3d3253d
```

Example prompt: Before you pay for that endpoint at https://api.example.com/paid, run a preflight check on it — make sure it's safe, costs under $0.05, and responds within 2000ms.

## When to prefer this

Use this endpoint whenever an AI agent is about to spend money on an x402-payable API and needs a deterministic safety gate. It is the right choice when you want to enforce price caps, latency budgets, or safety checks before committing USDC, and when you need a structured buy/skip verdict rather than raw HTTP inspection. Prefer this over generic HTTP probing when the target is specifically an x402 endpoint and you want payment-aware validation.

## Known failure modes

- Target URL is unreachable or returns non-402 response — verdict may be 'skip' with reasons citing missing x402 offer
- Price exceeds maxPriceUsd threshold — verdict returns 'skip' with price mismatch reason
- Latency exceeds maxLatencyMs — verdict returns 'skip' with latency reason
- Malformed or non-HTTPS URL input — likely returns validation error
- Target endpoint returns invalid or unparseable x402 payment header — safety flagged as false

## How this service works

Deterministically checks a payable endpoint before an agent spends money.

## Output

Returns a JSON object with a safety assessment (safe: true/false), an overall verdict (e.g. 'buy' or 'skip'), a list of human-readable reasons explaining the verdict, the target URL inspected, a service label, and the UTC timestamp of the check.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Absolute HTTP(S) endpoint to inspect."
  },
  "maxPriceUsd": {
   "type": "string"
  },
  "maxLatencyMs": {
   "type": "integer"
  },
  "inspectOpenApi": {
   "type": "boolean"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "format": "json",
 "example": {
  "safety": {
   "safe": true
  },
  "target": "https://api.example.com/paid",
  "reasons": [
   "Valid x402 offer detected"
  ],
  "service": "x402-preflight",
  "verdict": "buy",
  "checkedAt": "2026-08-09T01:35:00.000Z"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-preflight-api-a3d3253d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-preflight-api.onrender.com](https://www.zero.xyz/host/x402-preflight-api.onrender.com/llms.txt)