How do AI agents pay for APIs?
With x402, an agent's first request returns HTTP 402 with a payment challenge. The agent's x402 client signs a small USDC-on-Base authorization and resends the request with a payment header; the server verifies it and returns a 200 with the result. There is no signup, no API key, and no subscription — the agent settles a few cents per call autonomously.
How do AI agents pay for APIs?
Answer
With x402, an agent's first request returns HTTP 402 with a payment challenge. The agent's x402 client signs a small USDC-on-Base authorization and resends the request with a payment header; the server verifies it and returns a 200 with the result. There is no signup, no API key, and no subscription — the agent settles a few cents per call autonomously.
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
How do AI agents pay for APIs?
With x402, an agent's first request returns HTTP 402 with a payment challenge. The agent's x402 client signs a small USDC-on-Base authorization and resends the request with a payment header; the server verifies it and returns a 200 with the result. There is no signup, no API key, and no subscription — the agent settles a few cents per call autonomously.