Coinbase's x402 protocol enables AI agents to pay for APIs and data using stablecoins, activating the web's dormant HTTP 402 payment code.
AI & Agents ·
Coinbase launched x402, an open payment standard that repurposes the HTTP 402 status code—unused since the 1990s—to enable AI agents and applications to pay for APIs and data using stablecoins. The protocol primarily settles payments in USDC on Base, Coinbase's Ethereum layer-2 network, though it supports Solana, Polygon, Arbitrum and other chains alongside traditional card payments. Coinbase introduced x402 in May 2025 alongside partners including AWS, Anthropic, Circle and NEAR.
The protocol operates as a set of rules governing message formats and request-response flows within standard web communications. When an AI agent requests a service, the server responds with payment terms including price and accepted tokens; the client then signs a payment authorization with its wallet and resubmits the request. A facilitator handles most onchain settlement work, allowing transactions without account creation or API key management. Over 50 companies, including Visa, Mastercard and Google, have joined governance efforts; the x402 Foundation became fully operational under the Linux Foundation in July 2026.
The timing reflects a practical gap: with non-human traffic now exceeding half of internet activity and Cloudflare observing a billion 402 responses daily, traditional payment infrastructure designed for human users cannot accommodate micropayments between software agents operating autonomously across multiple services.