The x402 protocol is an open, HTTP-native payment standard for digital resources. Built on the HTTP 402 status code, it was created by Coinbase and is governed by the x402 Foundation. With x402, software can pay for APIs automatically with stablecoins such as USDC. It allows for AI agents to pay for APIs without the need for accounts, subscriptions or API keys.
What Is x402?
The x402 protocol enables the long-forgotten HTTP status code 402 Payment Required to become a functional payment channel on the web. Unlike many payment solutions that add a completely separate payment flow on top of the rest of the HTTP interactions, x402 payment is integrated into the request and response interactions on the web. A client requests a protected resource, a server responds with a payment offer, the client completes the payment, and the server returns the protected resource to the client.
Settlement is typically done using stablecoins such as USDC, which for both buyer and seller creates a programmable, internet-native unit of value. No need for a parallel billing channel.
x402 is also open, started by Coinbase but is designed to be used by anyone, including API vendors, without locking them into any specific Coinbase product. Governance of x402 is held by the x402 Foundation. This standard is of particular interest to those building autonomous software, machine commerce, or DeFAI systems more generally where models, wallets, and data services all interact through APIs and thus need to transact directly with one another.
