x402 Payments Protocol

x402 is an open payments protocol that uses HTTP’s 402 Payment Required status code to let a client pay for a resource in the course of requesting it, with no account, no signup and no prepaid credits. A resource server answers with a PaymentRequired object listing what it accepts, the client returns a signed payment payload, and a third role — the facilitator — verifies and settles it, usually in stablecoins on-chain. It deliberately separates transport (HTTP, MCP, A2A) from payment scheme (exact, upto, batch settlement) from network. Released by Coinbase on 6 May 2025 and contributed to the Linux Foundation, where the x402 Foundation became operational on 14 July 2026.