I Built an API That AI Agents Pay in USDC — Full x402 Walkthrough (27 Endpoints, Real Transactions)
I built an Express API that AI agents (or humans, or anything with fetch ) can pay per call, in USDC, with no signup and no API key. It's live on Base mainnet with 27 paid endpoints, and I've run real settled transactions against it. This is the technical walkthrough — the code, the protocol, and the things that actually broke — not an "agentic economy" pitch. What x402 is, in 5 lines x402…
I constructed an Express API that AI agents (or any entity capable of making HTTP requests) can pay for in USDC without needing any signup or API key. The platform operates on Base mainnet and has been tested with 27 paid endpoints, with actual transactions executed successfully. This detailed guide focuses on the code, underlying protocol, and real-world issues encountered, rather than promoting an agentic economy.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
