What Is x402? How AI Agents Pay With Crypto

In brief

• x402 is an open payment standard from Coinbase that uses the web's long-unused HTTP 402 code to let AI agents and apps pay for online services.
• Payments are mostly made in USDC on Base and settled through facilitators, so buyers sign an authorization instead of creating accounts or API keys.
• More than 50 companies, including Visa, Mastercard and Google, have joined the x402 Foundation, which now governs the protocol under the Linux Foundation.

Nobody really built the web with payments in mind. Early HTTP specifications included a status code, 402 "Payment Required", that was reserved for a future system of online payments. Then it sat unused for about 30 years. Payments were slow and expensive, and they needed accounts, card details and middlemen who could reverse charges. None of that works for a small payment made by software.

That gap matters more now because AI agents are starting to browse, call APIs and buy services for their users. An agent can't fill in a checkout form or sign up for a monthly plan for every tool it uses. Cloudflare says more than half of internet traffic is now non-human, and it reports seeing a billion HTTP 402 responses on its network every day.

x402 is an attempt to finally give the internet a native way to pay. This guide covers what it is, how it works, who backs it, and whether there's a token involved.