Hands-on guide for turning an existing site or API into a USDC pay-per-use business with Coinbase’s x402 protocol: how the 402 handshake actually works, what I learned wiring it into real code, and concrete pricing ideas for humans and AI agents.
Coinbase’s x402 protocol revives HTTP 402 “Payment Required” as a programmable payment handshake, so browsers and AI agents can pay websites directly using crypto. Here’s what x402 is, how the flow works in practice, and what it could mean for devs and on‑chain commerce.