Agentic Commerce Protocol (ACP)
Definition
The Agentic Commerce Protocol, or ACP, is an open protocol that OpenAI and Stripe announced on September 29, 2025, to standardize how an AI agent can complete a purchase on a merchant's behalf without the merchant having to build a custom integration for every agent. It defines how product information, pricing, and order details are exchanged between a merchant and an agent, as well as how the agent hands off payment.
ACP's core mechanism is a shared payment token: the person's actual card or bank details never pass through the merchant's own systems during an agent-initiated purchase, only a token that authorizes a specific transaction. ACP first powered ChatGPT's Instant Checkout, launched with a small number of Etsy merchants in the United States before expanding to more retailers.
ACP is one of several competing or overlapping standards for agentic commerce, alongside Google's Universal Commerce Protocol (UCP) and the authorization-focused Agent Payments Protocol (AP2). Payment networks have built their own compatible mechanisms on top, such as Mastercard's and Visa's Agentic Tokens, to let a card be used safely in an ACP-based transaction.
As of October 2026, ACP remains tied to OpenAI's own retreat from in-chat purchase completion (Agentic Checkout), announced in March 2026 in favor of connected merchant apps, though the underlying protocol is maintained for transactions that do go through apps. See the broader Agentic Commerce entry for the market context.
Examples
In 2025, an Etsy seller in the United States enabled Instant Checkout. A ChatGPT user asking for a handmade gift could complete the purchase without leaving the conversation, with Stripe processing the payment token behind the scenes via ACP.
A software company building its own shopping agent implements ACP once, rather than negotiating a separate payment integration with each merchant it wants its agent to be able to buy from.
Frequently Asked Questions
Who created the Agentic Commerce Protocol?
OpenAI and Stripe co-developed and announced ACP on September 29, 2025, as an open protocol any merchant or agent developer can implement.
Does ACP expose a customer's real card details to the merchant?
No. ACP relies on a shared payment token: the agent and payment processor handle the actual payment credentials, and the merchant only receives a token authorizing that specific transaction.
Is ACP the same as Instant Checkout?
No, ACP is the underlying protocol. Instant Checkout was OpenAI's own branded feature built on top of ACP, letting a purchase complete directly inside a ChatGPT conversation, before OpenAI pivoted that feature toward connected merchant apps in March 2026.
How does ACP relate to UCP and AP2?
ACP, UCP, and AP2 all address pieces of the same shift toward agentic commerce, but from different angles: ACP standardizes the purchase and payment handoff for OpenAI's ecosystem, UCP is Google's equivalent for its own AI surfaces, and AP2 focuses specifically on how a person authorizes an agent to pay at all. A merchant operating across several AI platforms may need to support more than one.
