x402
A proposed web standard that lets a server charge a tiny payment for a single request, so software can buy things without a signup form.
x402 is an attempt to make paying for something on the web as simple as loading a page. The name comes from HTTP status code 402, “Payment Required”, which was reserved in the original web standards decades ago and then essentially never used. The idea is that a server can answer a request with “that costs half a cent”, the caller pays, and the request completes, all without an account, a card form, or a subscription.
This matters mainly because of AI agents. An agent can read the web perfectly well but cannot buy anything, since every payment path assumes a human with a browser. x402 and the wallet systems built around it are the attempt to close that gap, usually with stablecoins as the money underneath.