x402 Lets Software Agents Pay for APIs Through HTTP Requests
Photo: TokenPost
The x402 open payment standard lets software request APIs and other digital services with payment terms carried in HTTP, allowing a client to authorize a charge as part of the same exchange. Coinbase introduced x402 on May 6, 2025. The protocol uses HTTP’s 402 Payment Required response, whose purpose RFC 9110 leaves open for future use. x402 uses that response to communicate that payment is needed and provide the requirements for it. A client begins by requesting a resource from an online service. If payment is required, the service can reply with a 402 response that includes payment requirements.
Source: TokenPost
