What is the x402 protocol?
x402 is an open payment protocol built on the HTTP 402 'Payment Required' status code. A server responds to an unpaid request with a 402 challenge describing the price, asset, network, and recipient; the client signs a stablecoin payment (USDC on Base) and retries; the server verifies and returns the result. It lets AI agents pay for APIs per request with no account or API key.
What is the x402 protocol?
Answer
x402 is an open payment protocol built on the HTTP 402 'Payment Required' status code. A server responds to an unpaid request with a 402 challenge describing the price, asset, network, and recipient; the client signs a stablecoin payment (USDC on Base) and retries; the server verifies and returns the result. It lets AI agents pay for APIs per request with no account or API key.
Why it matters for agents
Finance and quant agents need numbers they can defend. Routing the calculation to a deterministic, x402-metered endpoint gives the agent an audited result and a payment path it can perform autonomously — without API keys, subscriptions, or a data feed to manage.
Where to start
Browse the finance and quant suite on the agent services page, then point your agent's x402 client at an endpoint. The OpenAPI spec lists every endpoint with its inputs, price, and example.
FAQ
What is the x402 protocol?
x402 is an open payment protocol built on the HTTP 402 'Payment Required' status code. A server responds to an unpaid request with a 402 challenge describing the price, asset, network, and recipient; the client signs a stablecoin payment (USDC on Base) and retries; the server verifies and returns the result. It lets AI agents pay for APIs per request with no account or API key.