# Overwing Preflight for x402

> Overwing Preflight for x402 is a paid API for AI agents from overwing.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-14).

Evaluates an x402 payment-required challenge against an agent's spending policy and the x402 payee directory, returning allow/review/refuse with detailed reasons.

## Facts

- Endpoint: GET https://overwing.ai/api/x402/preflight/x402?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/overwing-preflight-for-x402-f9208b80
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gm89owztcPYXqOaN6Y8BI

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 overwing-preflight-for-x402-f9208b80
```

Example prompt: Before paying this x402 API challenge, run a preflight check against my policy — max $0.05 per call, no testnets, only USDC on base — and tell me if I should allow, review, or refuse it.

## When to prefer this

Use this endpoint when an AI agent encounters an x402 PAYMENT-REQUIRED response and must decide whether to sign and forward payment before proceeding. It is specifically suited for x402 v2 protocol challenges and provides directory-backed payee verification that generic policy checks cannot offer. Prefer it over manual policy evaluation when you need cross-referencing against the x402 payee registry and server manifest in a single low-cost call ($0.002 USDC, no account required).

## Known failure modes

- Malformed or undecodable PAYMENT-REQUIRED header returns a parsing error
- Unknown or unregistered payee returns a refuse with directory-miss reason
- Network not in allowed_networks list returns a refuse with network policy reason
- Price exceeds max_per_call_usd returns refuse with price policy reason
- Fresh quote fetch fails if requested_url is unreachable
- Policy object missing required fields may use defaults silently

## How this service works

Overwing Preflight for x402: should an agent sign this payment? POST the PAYMENT-REQUIRED terms and your policy; get allow, review or refuse with reasons: terms vs policy, payee vs the x402 directory and the server's own manifest, price vs the record. $0.002 USDC, no account.

## Output

A structured decision object containing one of: allow, review, or refuse; accompanied by specific reasons covering policy compliance (max per call, allowed networks, allowed/blocked payees, testnet flag, price drift), payee verification against the x402 directory and server manifest, and optionally a fresh-quote price comparison.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "policy": {
   "type": "object",
   "description": "max_per_call_usd (default 0.05), new_payee_max_usd (0.01), allowed_networks, allowed_payees, blocked_payees, allow_testnets (false), max_price_drift (0.25)"
  },
  "network": {
   "type": "string",
   "description": "The CAIP-2 network the agent would pay on, when the terms offer several"
  },
  "fresh_quote": {
   "type": "boolean",
   "description": "Also fetch the resource unpaid and compare its quote with the terms given"
  },
  "requested_url": {
   "type": "string",
   "description": "The URL the agent asked for; checked against the resource in the terms"
  },
  "payment_required": {
   "description": "The PAYMENT-REQUIRED header value (base64 JSON) or the decoded x402 v2 object {x402Version, resource, accepts[]}"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/overwing-preflight-for-x402-f9208b80/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from overwing.ai](https://www.zero.xyz/host/overwing.ai/llms.txt)