Agentic Commerce Protocol changing

What it is

The Agentic Commerce Protocol is how a merchant makes its catalog buyable from inside an AI assistant. OpenAI and Stripe published it in September 2025 alongside Instant Checkout in ChatGPT, starting with Etsy sellers and Shopify merchants. The merchant stays the merchant of record. The assistant is the storefront.

How it works

The merchant implements a small set of building blocks, each an OpenAPI spec in the repository:

• Checkout: create, update and complete a checkout session.
• Delegated payment: the assistant passes a scoped payment token, so the merchant charges through its existing processor without seeing raw card data.
• Product feed, orders and cart, added in the 2026-04-17 release.
• Authentication and MCP integration, also 2026-04-17.
• Extensions and discounts through capability negotiation.

Versions are dated snapshots, YYYY-MM-DD. The first was 2025-09-29 and the current one is 2026-04-17. The spec is Apache 2.0, maintained by OpenAI and Stripe as founding maintainers, with a stated path toward neutral foundation stewardship. It is marked beta.

When to use it

You sell things and want them purchasable in ChatGPT. Google’s surfaces use UCP instead, and the two overlap heavily. Expect to implement both if you care about both channels.

Watch out for

• The abbreviation ACP also means Zed’s Agent Client Protocol. Different worlds, same letters.
• Beta, with dated versions. Pin the version you implemented against.