x402

x402 is an open protocol that revives the long-dormant HTTP 402 "Payment Required" status code as a structured way for servers, agents, and clients to demand and pay for on-chain payments inline with normal HTTP interactions. When a resource is gated by x402, a 402 response carries the price, the accepted assets (typically stablecoins), the recipient address, and the facilitator URL; the client pays on-chain and retries the request with proof of payment. x402 matters to tokenized domains because it lets agents and apps using a domain as their identity collect payments cleanly — and because the controlling wallet of a tokenized domain doubles as a payment endpoint. See Route 402 for the deeper write-up. Official site: x402.org.