x402 Preflight

A pay-per-call check for AI agents: before your agent pays an x402 endpoint, ask Preflight what it will actually be charged.

Preflight sends one unpaid request to the target and reports the live price in USD, the network, whether the token is canonical USDC, the payTo address, the timeout, any mismatch with the CDP Bazaar listing, and a pay / caution / do_not_pay verdict. It never signs or pays anything for you.

Use

GET /api/preflight?url=<x402 endpoint>&method=GET&max_usd=0.05

Price: $0.01 USDC on Base (x402 v2, exact scheme). Any x402 client works.

Free: /api/health · /api/sample · /llms.txt · /.well-known/x402

Limits: https targets only, no IP literals or internal hosts, 8 s timeout. A clean challenge doesn't prove the seller will deliver. It shows the price, token and recipient are what your agent expects.