The Agentic Commerce Protocol (ACP) is an open specification, published by OpenAI, that enables a programmatic exchange between buyers, their AI agents, and sellers to complete a purchase. Agents render the checkout UI, collect buyer selections and payment credentials, and keep customers informed in real time, while sellers keep their existing back-end models and payment processing.

Flow

The flow ACP uses is the following:

1. The customer interacts with a LLM agent, asking to purchase a certain item or to look for something in general.
2. The agent retrieves a catalog of items from different merchant shops and provides the options to the customer.
3. The customer selects one or more items and moves to checkout.
4. The agent calls your backend using specific endpoints, described here, allowing them to create, update, or cancel a specific order.
5. The agent then uses previously-collected payment data to delegate the payment to us. We perform the store the credentials and return a payment token.
6. The agent calls your backend to complete the checkout, providing the payment token from the previous step.
7. Finally, as part of this call, you then need to call our charge endpoint with the provided token to finalize the payment.

What you need to do

ACP requires the implementation of the following APIs, according to their specification:

• create session POST /checkout_sessions.
• get session data GET /checkout_sessions/{id}.
• update session POST /checkout_sessions/{id}.
• complete session POST /checkout_sessions/{id}/complete - here you have to call our charge endpoint with the payment token offered by the agent in the API call.

Testing

At the current time (October 2026) there is no official testing environment to try this product. Instead you can use this demo app to play around and try the implementation. More details are present in the README of this repository.