Agentic Commerce Protocol (ACP) Explained: OpenAI, Stripe and ChatGPT Checkout

The Agentic Commerce Protocol (ACP) is an open standard from OpenAI and Stripe that defines how AI agents, buyers and businesses complete purchases. It covers checkout sessions, delegated payment credentials and, in newer versions, carts, product feeds, orders and an MCP binding.

ACP's first dated spec version is 2025-09-29, and it debuted with ChatGPT's Instant Checkout. OpenAI has since changed course: ChatGPT now sends shoppers to merchant-owned checkout, while ACP remains "the open infrastructure for AI-native commerce in ChatGPT." This guide explains what ACP is, where it stands and what merchants should do, checked on 6 November 2026.

Which ACP this page covers

Three different projects use the letters ACP:

Zed describes the Agent Client Protocol as "an open standard that enables any agent to integrate seamlessly with any editing environment." IBM's ACP project page says "ACP is now part of A2A under the Linux Foundation!" For that lineage, see what the A2A protocol is.

From here on, "ACP" means the Agentic Commerce Protocol.

What ACP is

The ACP website calls it "An open standard for programmatic commerce flows between buyers, AI agents, and businesses." It says businesses keep control of their customer relationships. Key promises on the site:

• Checkout that any compatible agent can start, configured by the business
• Support for physical and digital goods, subscriptions and asynchronous purchases
• Payment credentials handled so agents do not see the underlying card details
• Integration through REST or MCP

The site describes OpenAI as "the first AI platform to implement ACP with ChatGPT" and Stripe as the first compatible payment service provider, using its Shared Payment Token.

Who runs ACP

The ACP GitHub repository says the specification is "maintained by OpenAI and Stripe and is currently in beta." It states that "ACP is jointly governed by OpenAI and Stripe as Founding Maintainers," with consensus-based decisions and "Neutral foundation stewardship" named as the future path.

The repo's maintainers file lists three lead maintainers: OpenAI, Stripe and Meta.

So, as of November 2026, ACP is a company-led open standard. It is not hosted by a foundation.

What the spec covers

ACP uses dated versions: 2025-09-29, 2025-12-12, 2026-01-16, 2026-01-30 and 2026-04-17, which the README marks as the latest stable. The core pieces are:

• Agentic Checkout spec: the API a merchant implements so an agent can create, update and complete a checkout.
• Delegated Payment spec: how a payment provider issues a scoped token so the agent never handles raw card data.

The 2026-04-17 changelog added a lot:

• Cart: "pre-checkout cart management for incremental basket building."
• Feed API: described as an "unreleased Feed API surface" for catalog management, where merchants push data to the agent.
• Orders: "rich post-purchase order tracking with line items, fulfillments, and adjustments."
• Delegated authentication: a flow for 3DS2 card checks.
• MCP transport binding: "Model Context Protocol (MCP) transport binding for ACP checkout operations," with five tools mapping to the checkout endpoints.
• Discovery: a /.well-known/acp.json document.
• Idempotency: an Idempotency-Key header is now required on POST requests.

ChatGPT checkout: what changed

The launch

ACP debuted with Instant Checkout in ChatGPT. The first dated ACP spec is 2025-09-29. Our older posts on ChatGPT Instant Checkout describe that launch.

The change in direction

The ChatGPT merchants page, checked on 6 November 2026, confirms the direction:

• "We're moving away from a standalone Instant Checkout experience in ChatGPT."
• "Users can discover and evaluate products in ChatGPT, but purchases are completed on merchant-owned websites or apps."
• "There are no fees on purchases that start in ChatGPT."
• "Shopping is currently live in the U.S. and will expand to additional regions over time."
• "Most merchants start with product feeds," and "Apps are optional and are best suited for larger merchants."
• "The Agentic Commerce Protocol (ACP) is the open infrastructure for AI-native commerce in ChatGPT."

How merchants get in

OpenAI's commerce get-started guide says "Onboarding product feeds in ChatGPT is currently available to approved partners." You apply at chatgpt.com/merchants. Feeds upload over SFTP, and OpenAI recommends "uploading a full snapshot at least once a day."

Larger merchants can also build a ChatGPT app. See MCP vs ChatGPT Apps SDK for how apps relate to MCP.

Where Stripe fits

Stripe's agentic commerce docs cover Shared Payment Tokens ("scoped payment credentials for agent-initiated purchases"), a catalog feed, and guides for selling to agents. The same docs also link Stripe's UCP support and machine payments such as MPP and x402. Stripe works with both ACP and UCP, which is useful if you sell through several AI channels.

How ACP relates to MCP, UCP and AP2

• MCP: ACP can run over MCP since the 2026-04-17 binding. MCP is the transport; ACP defines the commerce actions.
• UCP: a separate commerce standard led by Google and Shopify. See UCP vs ACP.
• AP2: Google's payment authorization protocol, now at the FIDO Alliance. ACP uses delegated payment tokens instead. See the AP2 explainer.

What merchants should do now

1. Apply for ChatGPT product feeds if you sell in the U.S. and fit OpenAI's partner criteria.
2. Make your own checkout fast. ChatGPT shoppers now finish on your site or app.
3. Ask your platform about ACP. Most merchants will not implement the spec directly.
4. Build to ACP only with a reason. If you run a custom stack and an AI platform asks for ACP, start from the 2026-04-17 spec and expect beta changes.
5. Track both standards. UCP and ACP overlap, and many payment providers support both.

Next step

eSEOspace builds ChatGPT apps on MCP through our ChatGPT app development service, and designs stores through our ecommerce services. We scope and quote every project and cannot promise placement in ChatGPT. For the wider picture, see the agent protocols hub.

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