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 Governance Council (Google, Shopify, Stripe) over per-domain Tech Councils: Shopping (16 seats, 10 companies), Food (seated July 2026), and Lodging (seated August 2026)
Launched	September 2025	January 2026
Current revision	`2026-04-17`, status beta	`v2026-08-25`
Scope	The agent-to-merchant checkout	The whole shopping journey, and now beyond retail into lodging and food
Primary surface	ChatGPT	Google Search (AI Mode), Gemini
Payment	Shared Payment Token	Open payment-handler model; pairs with AP2; Google Pay in Google’s implementation
License	Apache 2.0	Apache 2.0
What is live	Etsy from launch; native in-chat checkout moved to Apps in March 2026	Checkout in AI Mode and Gemini for eligible US retailers; Universal Cart checkout and Canada, Australia and UK expansion announced May 2026

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 governed in two layers. Per-domain Tech Councils steward the specification. The Shopping Tech Council went to sixteen seats on 24 April 2026 when Amazon, Meta, Microsoft, Salesforce, and Stripe joined the founding group of Google, Shopify, Etsy, Target, and Wayfair; all sixteen are filled, across those ten companies. A Food Tech Council followed on 16 July 2026 with Block (Square), DoorDash, Google, Toast, and Uber Eats, and a Lodging Tech Council on 11 August 2026 with Amadeus, Booking.com, Expedia, Google, Hilton, Marriott, and Trip.com. Above them sits a Governance Council: Google and Shopify, joined by Stripe on 28 April 2026, with two further seats open for election. Google holds four of the sixteen Shopping seats and six of the ten filled Food seats, so the largest single voice inside UCP governance is still Google’s.

The detail worth noting is the overlap, and it has deepened. Stripe is a founding maintainer of ACP and now sits on both UCP councils, and it documents integrations for both protocols. Meta is a lead maintainer of ACP and a member of the UCP Tech Council. That is a clear signal that the field is still settling and that the big players are hedging rather than picking a winner. 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 in March 2026 OpenAI said Instant Checkout was “moving to Apps,” repositioning toward discovery that hands shoppers to the merchant’s own checkout, with ACP serving as the underlying infrastructure. 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. At Google Marketing Live on 20 May 2026 Google said its Universal Cart checkout would reach retailers including Nike, Sephora, Target, Ulta Beauty, Walmart, Wayfair, and Shopify merchants “soon,” and that UCP-powered checkout would roll out in Canada and Australia in the coming months and later the UK. Read that carefully: much of the UCP news is announced rather than shipped. Both standards 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 defines an open payment-handler model, pairs with AP2 for payment authorization (the signed mandate that proves the user approved the purchase), and, in Google’s own implementation, settles through Google Pay, with PayPal named at launch as a coming option and Affirm and Klarna buy-now-pay-later options announced for Google Pay in May 2026. 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. Stripe now documents integrations for both protocols side by side, which is the clearest practical sign 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.