In short. OpenAI documents ACP product feeds and checkout sessions, with merchants controlling order acceptance and payment processing.

Definition: Agentic Commerce Protocol (ACP) is an open standard connecting merchants with AI shopping agents. OpenAI's implementation documents structured product feeds for ChatGPT and checkout interfaces that keep order decisions and payment processing on merchant systems.

Key facts

As of 17 October 2026, OpenAI's ACP overview describes structured catalog ingestion and merchant inventory information for ChatGPT shopping.
OpenAI's Products reference separates product feed requirements from a separately enabled checkout integration.
The Get Started guide limits product feed onboarding to approved partners and recommends daily full feeds with updates through the API during the day.
The Agentic Checkout Spec describes checkout sessions, merchant endpoint calls and order event webhooks.

What does a merchant catalog contain?

A product feed is structured catalog data supplied to OpenAI. The Products reference identifies Stable as the supported file upload schema; Draft is for planning and feedback.

The OpenAI-format basic fields are item_id, title, description, url, brand, seller_name, image_url, availability and price. Each purchasable item or variant occupies a separate row. Product and image URLs must be publicly accessible, and identifiers remain strings to preserve leading zeros.

For variants, each row has a distinct item_id, a shared group_id, listing_has_variations=true and a variant_dict describing the selected options. Each row carries its own price, availability, URL and images. The reference also supports return information through accepts_returns, return_deadline_in_days and return_policy; a policy URL alone does not set return acceptance.

How does the checkout specification work?

A checkout session holds the items, fulfillment information and payment information for a purchase. OpenAI's Agentic Checkout Spec lists these merchant endpoints:

POST /checkout_sessions
POST /checkout_sessions/{checkout_session_id}
POST /checkout_sessions/{checkout_session_id}/complete
POST /checkout_sessions/{checkout_session_id}/cancel
GET /checkout_sessions/{checkout_session_id}

The create call starts the session. Updates return revised costs, fulfillment options and errors as the shopper changes checkout details. The completion endpoint receives payment data and returns the resulting checkout state, including an order when created. The other endpoints cancel a session or retrieve its current information.

All endpoints use HTTPS and return JSON. Responses carry the cart state needed to display items, costs and status. The specification also describes order events such as order.created and order.updated, delivered through webhooks, which are notifications sent to an endpoint when order state changes. Its security guidance calls for request authentication, signature verification and idempotency, which allows retries without repeating an operation's effect.

Who controls orders and payments?

OpenAI's Key concepts guide assigns order acceptance or refusal to the merchant. ChatGPT collects buyer, fulfillment and payment information and displays the resulting state. The merchant validates the purchase, determines fulfillment options and handles tax and payment processing on its systems.

A payment service provider (PSP) processes the merchant's payments. The Delegated Payment Spec lets OpenAI share payment details with the merchant or its designated PSP. The guide describes a one-time request restricted by a maximum chargeable amount and an expiry, followed by a payment token used to complete payment. The merchant remains responsible for payment processing through its PSP.

FAQ

Does a product feed activate checkout?

Checkout requires a separately enabled integration under the Products reference. Search is enabled and checkout disabled by default in its minimal OpenAI-format example.

How should you keep catalog data current?

The Get Started guide recommends a daily full feed through file upload and API updates during the day. For a small feed, you can send both the full catalog and regular updates through the API.

Who is the merchant of record?

The merchant retains that role. OpenAI's Key concepts guide places checkout state and payment processing on the merchant's systems and states that merchants bring their own PSP.

Sources

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