One paid call for 0.001 USDC that settles a real payment and answers immediately: the cheapest way to prove a wallet, a facilitator and a network before spending on a data call. It reads no third-party source, so a failure is your integration or ours, never somebody else's uptime. The response names the rail that settled it and the network mode. Payable on Base, Polygon, Arbitrum and XDC.