What Is x402? The HTTP Payment Standard Built for AI Agents, Explained (opens in new tab)

TL;DR: x402 is an open standard that lets software, including AI agents, pay for APIs, data, and services directly over HTTP using stablecoins, with no accounts, API keys, or human checkout. It puts the web's unused 402 Payment Required status code to work as a native payment layer. The web reserved a status code for payments in 1996 and then left it empty for thirty years. AI agents just gave it a job. Every developer has met 404 Not Found. Most have fought 403 Forbidden. But sitting quietly...