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What Is x402? How AI Agents Pay With Crypto
Coinbase's x402 protocol puts the web's long-unused 402 code to work so AI agents and apps can pay for APIs and data in stablecoins like USDC.
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.
