Agent payments (x402)

Card networks and bank accounts assume a human customer with an identity and a billing address. An AI agent that needs to buy one search result, one dataset or a few seconds of compute has none of that, but it can hold a wallet. Agent payment protocols let software pay per request in stablecoins and receive the service immediately, without accounts, subscriptions or API keys.

The best-known example is x402, an open protocol introduced by Coinbase in 2025 that revives the long-unused HTTP status code 402 Payment Required. A server replies to a request with a price and payment details, the client signs a stablecoin payment and retries with proof attached, and a facilitator verifies and settles it on-chain. Other technology and payment companies have proposed related standards for authorising agents to pay on a user's behalf.

Usage is still early and much of the activity so far has been experimental or incentive-driven. Open questions include who is liable when an agent pays the wrong party, how spending limits and refunds work, and how merchants handle tax and compliance for anonymous machine customers.