the dormant code
Reserved in 1997. Left empty for ~30 years.
402 Payment Required has been in the HTTP spec since the early web, marked "reserved for future use" and almost never implemented. It was the internet's promise to itself that one day the web would know how to charge for things — a promise left blank for a generation.
x402 is the open protocol (from Coinbase, now under neutral governance) that finally wires it up: a server answers a request with 402 and payment instructions, the client signs a stablecoin payment, and the same HTTP round-trip settles onchain — no accounts, no API keys, humans and AI agents alike, in about a second on Base.
Simple things make impossible things possible on Base.