Are ACP and UCP rivals?

At the commerce and checkout layer, yes, they are the one genuine rivalry in the stack. But several large companies back both (Stripe and Meta among them), both are Apache 2.0, and a merchant can implement both, so it is less a winner-take-all fight than two overlapping standards that are still settling.

How does payment differ between ACP and UCP?

ACP carries its own payment mechanism, the Shared Payment Token, a single-use credential scoped to one merchant and one cart total. UCP leans on the rest of the stack: it pairs with AP2 for payment authorization and, in Google's reference implementation, settles through Google Pay. So ACP bundles the token; UCP composes with separate authorization and payment layers.

ACP vs UCP: Comparing the Two Agentic Commerce Checkout Standards

Q: What is the difference between ACP and UCP?

ACP, the Agentic Commerce Protocol from OpenAI and Stripe, is the narrower standard: it covers the agent-to-merchant checkout handshake and is live on ChatGPT surfaces. UCP, Google's Universal Commerce Protocol, is broader: it aims at the whole shopping journey from discovery through checkout to post-purchase, and is live in Google Search's AI Mode and the Gemini app. They overlap at the checkout step, which is where they genuinely compete.

Q: Should a merchant support ACP or UCP?

It depends on where your customers shop. If ChatGPT is a meaningful surface for you, ACP is what makes you buyable there; if Google Search and Gemini matter, UCP does. Because the two surfaces reach different audiences and several platforms syndicate to both, many merchants should plan to support both rather than choose.

ACP and UCP are the two open standards for letting an AI agent complete a purchase. They are often cast as rivals, and at the checkout step they do overlap, but they are not the same shape. The Agentic Commerce Protocol (ACP) is the narrower one: an OpenAI and Stripe standard for the agent-to-merchant checkout handshake, live on ChatGPT surfaces. The Universal Commerce Protocol (UCP) is Google’s broader standard for the whole shopping journey, from discovery through checkout to post-purchase, live in Google Search’s AI Mode and the Gemini app. Both are licensed Apache 2.0, and several large companies back both, so for many merchants the real question is not which to pick but whether to support both.

At a glance

	ACP	UCP
Full name	Agentic Commerce Protocol	Universal Commerce Protocol
Led by	OpenAI and Stripe founding governance; OpenAI, Stripe, and Meta listed as lead maintainers	Google, with a Tech Council
Launched	September 2025	January 2026
Scope	The agent-to-merchant checkout	The whole shopping journey
Primary surface	ChatGPT	Google Search (AI Mode), Gemini
Payment	Shared Payment Token	Pairs with AP2, via Google Pay
License	Apache 2.0	Apache 2.0
What is live	Etsy from launch; native in-chat checkout scaled back in early 2026	Checkout in AI Mode and Gemini for eligible US retailers

What each one is

ACP standardizes the conversation at checkout between a buyer’s agent and a merchant: creating, updating, and completing a checkout session, passing a payment token, and confirming the order. Its purpose is narrow and practical, so a merchant builds one integration instead of a different one for every agent surface. For the detail, see ACP explained.

UCP is wider by design. Where ACP begins at checkout, UCP aims to standardize the entire shopping journey: catalog search, cart building, checkout, identity linking, the order lifecycle, and a payment-token exchange. It treats payment as one composable piece rather than something baked in. For the detail, see UCP explained.

Scope: a narrow handshake versus the whole journey

This is the central difference. ACP is a checkout handshake; UCP is a journey. If you only need agents to be able to buy from you, ACP does that one job well. If you want agents to discover, compare, buy, and handle post-purchase through a single standard, that is the broader ground UCP is trying to occupy. The two meet, and compete, precisely at the checkout step, which is why they are described as rivals even though most of UCP’s surface area has no ACP equivalent.

Who is behind each

ACP was launched by OpenAI and Stripe in September 2025. Its 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, so it backs both. ACP is governed with a stated path toward broader, more neutral stewardship.

UCP is Google-led, launched in January 2026, and steered by a Tech Council. That council doubled to ten members in April 2026 when Amazon, Meta, Microsoft, Salesforce, and Stripe joined the founding group of Google, Shopify, Etsy, Target, and Wayfair. The detail worth noting is the overlap: Stripe and Meta back both standards, a clear signal that the field is still settling and that big players are hedging. The full picture is in the landscape.

What is actually live

Adoption is where the two diverge most, and a neutral reference should be plain about it. On the ACP side, Etsy was live from launch for US buyers, but only a small number of merchants integrated, and OpenAI scaled back native in-chat Instant Checkout in early 2026, repositioning toward apps and discovery that hand shoppers to the merchant’s own checkout. On the UCP side, Google’s protocol powers checkout inside AI Mode in Search and the Gemini app for eligible US retailers, paying through Google Pay. Both are real, but they are live on different surfaces reaching different audiences, which matters more for planning than any feature comparison.

How payment works in each

ACP carries its own payment mechanism. At checkout, the payment provider issues a Shared Payment Token, a single-use credential scoped to one specific merchant and one specific cart total, which the agent passes to the merchant to charge. The agent never sees the raw card, and the token cannot be reused.

UCP leans on the rest of the stack rather than bundling payment. It pairs with AP2 for payment authorization (the signed mandate that proves the user approved the purchase) and, in Google’s reference implementation, settles through Google Pay. So ACP packages the token; UCP composes with separate authorization and payment layers. For the mechanics underneath both, see how AI agents pay.

Do they compete or compose?

Both. They compete at the commerce-and-checkout layer, which is the one genuine rivalry in the agentic commerce stack. But they also compose with everything around them, and to a degree with each other: a merchant can implement both, and the platforms many merchants sell through are moving to syndicate to multiple agent surfaces at once. The presence of Stripe and Meta on both sides reinforces that this is not yet a winner-take-all contest. For where both sit among the other standards, see the protocol stack.

Which should a merchant support?

The honest answer is to follow your customers, not the standards. If ChatGPT is a meaningful surface for your audience, ACP is what makes your products buyable there. If Google Search and Gemini are where your customers are, UCP does the same for those surfaces. Because the two reach different audiences, and because supporting both is increasingly a platform feature rather than two separate builds, many merchants should plan for both and weigh the economics of each surface (including any per-sale fees) rather than betting on a single winner. The wider decision of whether and how fast to move is worked through in what agentic commerce means for your business.

FAQ

What is the difference between ACP and UCP? ACP is the narrower OpenAI and Stripe standard for the agent-to-merchant checkout, live on ChatGPT. UCP is Google’s broader standard for the whole shopping journey, live in Google Search’s AI Mode and Gemini. They overlap, and compete, at the checkout step.

Are they rivals? At the checkout layer, yes, the one genuine rivalry in the stack. But both are Apache 2.0, several companies back both, and a merchant can implement both, so it is two overlapping standards still settling rather than a winner-take-all fight.

Should a merchant support ACP or UCP? Follow your customers. ChatGPT audience points to ACP; Google Search and Gemini audience points to UCP. Many merchants should plan to support both.

How does payment differ? ACP carries its own Shared Payment Token, scoped to one merchant and one total. UCP pairs with AP2 for authorization and settles through Google Pay in Google’s implementation.