# x402 Preflight

> Check any x402 endpoint before paying it. One unpaid probe returns live price (USD), network, canonical-USDC check, payTo, timeout, CDP Bazaar listing mismatches, and a pay / caution / do_not_pay verdict.

- Paid endpoint: GET /api/preflight?url=<absolute https x402 URL>&method=GET|POST&max_usd=<optional ceiling>
- Price: $0.01 USDC on Base (eip155:8453), x402 v2 exact scheme
- Free: /api/health, /api/sample
- Never signs or pays on your behalf. POST targets are probed with an empty JSON body.