How does payment work in ACP without sharing card details?

The buyer pays through an inline checkout and the payment service provider issues a Shared Payment Token scoped to one specific merchant and one cart total. The agent passes that token to the merchant, who charges it. The raw card credentials are never exposed to the agent.

ACP Explained: The Agentic Commerce Protocol

Q: Who maintains ACP?

ACP's README describes OpenAI and Stripe as the founding maintainers that jointly govern the project, while MAINTAINERS.md lists OpenAI, Stripe, and Meta as lead maintainers. Meta also sits on the rival UCP Tech Council, so it remains tied to both commerce-layer efforts. ACP is licensed under Apache 2.0, with a stated path toward broader community governance.

Q: Did a million Shopify merchants go live on ACP?

No. The 'over a million Shopify merchants' line was an announced ambition, not a live fact. Only a small number of Shopify merchants integrated, and trade reporting indicates OpenAI scaled back native Instant Checkout in early 2026. Etsy was genuinely live from launch.

The Agentic Commerce Protocol (ACP) is an open standard for letting an AI agent complete a purchase with a merchant. Its purpose is narrow and practical: give agents and stores a shared language for checkout so a merchant builds one integration instead of a different one for every AI platform.

Who is behind it

ACP was launched on 29 September 2025 by OpenAI and Stripe, and it powered the original “buy it in ChatGPT” Instant Checkout experience. The project’s README describes OpenAI and Stripe as the founding maintainers that jointly govern the project, while MAINTAINERS.md lists OpenAI, Stripe, and Meta as lead maintainers. Meta is also a member of the rival UCP Tech Council, so it remains tied to both commerce-layer efforts. ACP is licensed under Apache 2.0 and governed through a public proposal process, with a stated intention to move toward broader, more neutral stewardship over time.

What ACP actually does

ACP standardizes the checkout conversation between a buyer’s agent and a merchant. The specification covers agentic checkout (creating, updating, and completing a checkout session), cart and product feed, delegated payment, delegated authentication via OAuth 2.0, and orders and webhooks for confirmation, shipping, delivery, and refunds.

Crucially, the merchant stays in control. They remain the merchant of record and keep the customer relationship, fulfillment, returns, tax, and support. ACP is the handshake at the checkout, not a takeover of the store.

It is just as important to be clear about what ACP is not. It is not a tool-discovery protocol, that job belongs to MCP. It is not an agent-identity or attestation layer. And it is not a crypto-settlement protocol. ACP describes itself as compatible with both plain REST and MCP, and it deliberately leaves those adjacent layers to other standards.

How payment flows

This is the part most people get wrong, so it is worth being precise. When a buyer checks out, the payment service provider (Stripe in the reference implementation) issues a Shared Payment Token: a single-use credential that is scoped to one specific merchant and one specific cart total. The agent, for example ChatGPT, passes that token to the merchant through the ACP interface, and the merchant charges it through their own processor.

The point of the design is that the agent never sees the buyer’s actual card details, and the token cannot be reused for a different amount or a different merchant. Merchants already on Stripe can enable it with minimal code; merchants on other processors can adopt it through the Shared Payment Token API or the protocol’s Delegated Payments specification.

1BuyerPay
The buyer pays through the inline checkout.
2ProviderTokenize
The payment provider issues a token, scoped to one merchant and one total.
3AgentHand off
The agent passes the token on, never the card.
4MerchantCharge
The merchant charges it; the token cannot be reused.

A single-use token moves instead of the card, locked to one merchant and one amount.

What is actually live

Here the gap between announcement and reality matters, and it is the single most misreported part of ACP’s story.

Etsy was genuinely live from day one for US buyers. Walmart announced a partnership on 14 October 2025 to let ChatGPT users buy most of its catalog. PayPal announced on 28 October 2025 that it would adopt ACP to bring its merchant network into ChatGPT.

The widely repeated claim that “over a million Shopify merchants” went live is not accurate. That figure was an announced ambition described as “coming soon,” and only a small number of Shopify merchants actually integrated. According to trade reporting, in early 2026 OpenAI scaled back native Instant Checkout, repositioning the in-chat “buy now” experience toward ChatGPT Apps and product discovery that sends shoppers to a merchant’s own checkout. The protocol itself continues as the connective infrastructure, but the flagship “buy directly inside the chat” moment was pulled back. The lesson is that adoption of a standard depends as much on the host surface promoting it as on the standard itself.

The specification is officially in beta, and the latest stable version as of mid-2026 is dated 2026-04-17, following a steady cadence of releases that added fulfillment, capability negotiation, discounts, payment handlers, cart, feed, orders, authentication, and MCP support.

Where it sits in the wider landscape

ACP is the checkout layer. Around it sit several other standards that mostly compose with it rather than replace it: AP2 handles payment authorization and trust, MCP handles discovery, and x402 handles machine-native stablecoin settlement. The one genuine rival at the commerce-semantics layer is Google’s Universal Commerce Protocol (UCP), launched in January 2026 with backers including Shopify, Etsy, Target, Wayfair, and Walmart, which aims at the broader shopping journey rather than checkout alone. In April 2026 its Tech Council doubled to ten members as Amazon, Meta, Microsoft, Salesforce, and Stripe joined. Notably, Stripe and Meta are associated with both efforts, a sign the standards are still settling. For a side-by-side, see ACP vs UCP; for the full map, see the protocol stack.

What it means for you

If you are a merchant, ACP is one of the two checkout-layer standards worth tracking, alongside UCP. Adopting it is what makes your products buyable from an agent surface that supports it; for a step-by-step integration, see how to implement ACP. If you are a builder, treat ACP as the checkout handshake and pair it with a discovery layer and a payment-authorization layer rather than expecting it to do everything. And whatever you read about adoption numbers, check whether a partner is actually live or merely announced.

FAQ

Who maintains ACP? ACP’s README describes OpenAI and Stripe as founding maintainers, while MAINTAINERS.md lists OpenAI, Stripe, and Meta as lead maintainers. Meta also sits on the rival UCP Tech Council. It is Apache 2.0 licensed.

Did a million Shopify merchants go live on ACP? No. That was an announced ambition, not a live fact. Only a handful of Shopify merchants integrated, and OpenAI scaled back native Instant Checkout in early 2026. Etsy was genuinely live from launch.

How does payment work without sharing card details? A Shared Payment Token, scoped to one merchant and one cart total, is issued and passed to the merchant. The agent never touches the raw card credentials.