Agentic Commerce Protocol (ACP)

Definition

The Agentic Commerce Protocol (ACP) is an open standard for completing purchases through an AI agent. It was released by OpenAI and Stripe on September 29, 2025, is published under the Apache 2.0 licence, and is the protocol behind Instant Checkout in ChatGPT.

ACP defines the interaction model between three parties: a buyer, the buyer’s agent, and the merchant. It is deliberately narrow — it does not tell you how to merchandise, price, or fulfil. It standardises the handshake.

The three capabilities

1. Machine-readable product discovery. Structured feeds an agent can parse without scraping a rendered page. This is where most merchants discover their catalog is weaker than they assumed.
2. Conversational checkout with stateful negotiation. The agent and merchant exchange cart state, availability, shipping options and totals across turns, rather than the agent driving a browser through a form.
3. Payment via delegate tokens. The buyer’s payment credential is not handed to the agent. A scoped, delegated token authorises a specific purchase, which is what makes the model tolerable to risk and fraud teams.

What a merchant actually has to do

Supporting ACP is not primarily an integration project. In rough order of effort:

• Fix the catalog. Attribute completeness against what agents compare on in your category, structured variants, and specifications lifted out of prose description fields. This is the long pole and the part that pays off under UCP too.
• Expose a conformant feed. Machine-readable, current, and consistent with what your storefront actually shows.
• Support the checkout handshake. If you are on a major platform, expect a growing share of this to arrive as a platform feature — check before building it.
• Decide your payment path. Stripe’s implementation is the most documented route; the spec itself is open.

When not to prioritise it

If your traffic does not meaningfully touch ChatGPT, waiting is a defensible position and we will say so. Two conditions change that calculus: a category where comparison shopping dominates (electronics, appliances, components) where agents are disproportionately useful, and a competitor already appearing in agent results where you do not.

The catalog work, by contrast, has no good reason to wait. It is required under both standards, it improves conventional search, and it was worth doing before agents existed.

How it differs from UCP

ACP follows ChatGPT traffic; the Universal Commerce Protocol follows Google surfaces. ACP is scoped tightly around discovery, checkout and payment. UCP covers a broader journey including post-purchase support. Most merchants at scale will eventually need both — see our ACP vs UCP comparison.

What it is not

ACP is not AgentCore Payments, which covers agent-to-API microtransactions against a session budget rather than a consumer purchase. It is also not a replacement for your storefront: an ACP purchase still lands in your order system, your fulfilment, and — critically — your PCI scope.

Related terms

Agentic commerce · Universal Commerce Protocol · Agent checkout · Product feed · Model Context Protocol