Universal Commerce Protocol (UCP): what it is, how it works and what it means for your store

The Universal Commerce Protocol (UCP) is an open standard that lets AI assistants search a store’s products, put them in a cart and check out, without every assistant needing its own integration. Google announced UCP on January 11, 2026. It is no longer a proposal: in the United States UCP powers checkout in Google’s AI Mode and the Gemini app, and since October 15, 2026 also Universal Cart.

This article explains what UCP is, how it works technically, how Google uses it and how it differs from OpenAI’s Agentic Commerce Protocol. Then what your store should do with it now. The overview of all AI platforms and the steps per store platform are in agentic commerce for Shopify, WooCommerce and Magento.

What is UCP?

UCP is a shared language between AI assistants and stores for the whole buying journey, from search to order. Google announced it on January 11, 2026, developed together with Shopify, Etsy, Wayfair, Target and Walmart. More than twenty other parties back it, including Adyen, American Express, Best Buy, Mastercard, Stripe, The Home Depot, Visa and Zalando.

A few characteristics:

• Open. The specification is on ucp.dev under the Apache 2.0 license. Contributions go through GitHub.
• The store stays the seller. Google writes that the retailer remains the seller of record, also when the customer checks out in AI Mode or Gemini.
• Works with other protocols: A2A (Agent2Agent), AP2 (Agent Payments Protocol) and MCP (Model Context Protocol).

Which problem does UCP solve?

Without a shared standard, every AI assistant needs its own integration with every store. UCP replaces those separate integrations with one language. Shopify, which co-developed UCP, writes in its explanation of agentic commerce that checkout rules, discounts and terms therefore stay the same in every assistant, and that merchants need no extra integration when a new AI platform adopts UCP.

How does UCP work technically?

UCP has two roles: the platform (the AI assistant or agent acting on behalf of the buyer) and the business (the store). They find each other through a profile, agree on what they both support, and then exchange data over fixed capabilities.

Discovery: the profile at /.well-known/ucp

A store publishes its profile at /.well-known/ucp on its own domain. That is a JSON file with, among other things, the UCP version, the transports the store supports, its capabilities, payment options and public keys. According to the specification, the agent sends a link to its own profile with every request. The store then determines which capabilities both parties support, and per capability the highest version they both know. Versions are named by date, in the form YYYY-MM-DD.

The capabilities: from catalog to order

For stores, the specification describes these capabilities:

• Catalog: searching and browsing the assortment.
• Cart: building and managing a cart with several items.
• Checkout: a checkout session.
• Identity Linking: linking the customer’s account at the store, through OAuth 2.0.
• Order: status updates through webhooks, tracking and returns.

Beyond stores, UCP is working on other sectors. A draft booking capability exists for lodging, and food is on the roadmap.

Payment

Payments run through AP2, with what the specification calls payment mandates and verifiable credentials: according to ucp.dev, every payment is tied to cryptographic proof that the customer gave consent. Connections can run over REST, JSON-RPC, MCP or A2A.

How does Google use UCP?

Google uses UCP to let buyers check out in AI Mode and the Gemini app, for now in the United States.

Merchant Center remains the foundation. In its merchant documentation, Google writes that your existing product feeds in Merchant Center make sure your products are found. For checkout, native checkout is the default: you connect your checkout logic directly to AI Mode and Gemini. An embedded checkout in an iframe is an extra option for approved merchants with a complex or highly custom checkout. You sign up through a waitlist.

January 2026: checkout in AI Mode and Gemini. At the announcement, Google said UCP would soon power checkout at eligible US retailers, with Google Pay and later PayPal. According to Shopify, selected brands can now check out in AI Mode and Gemini, with a broader rollout on the way.

May 2026: Universal Cart announced. At Google Marketing Live (May 20, 2026), Google presented Universal Cart: one cart for products from several stores, in Search and Gemini. The customer checks out with Google Pay or sends the products to the store’s site; the store always stays the seller. Google also announced that brands with a UCP integration can sell directly through Direct Offers and Shopping ads on YouTube and in Demand Gen campaigns.

October 15, 2026: Universal Cart live in the US. According to The Next Web, the cart also alerts shoppers to price drops and restocks, and looks for discount codes. Canada and Australia follow within months according to Google, then the United Kingdom.

What is the difference between UCP and ACP?

UCP and OpenAI’s Agentic Commerce Protocol (ACP) are both open standards for AI commerce, but in October 2026 they do different things.

	UCP	ACP
Developed by	Google with Shopify, Etsy, Wayfair, Target and Walmart	OpenAI with Stripe
Used in	Google AI Mode, Gemini, Universal Cart; according to Shopify also Copilot Checkout	ChatGPT
What it handles	Catalog, cart, checkout, account linking, orders	Since March 2026 mainly product feeds and promotions for discovery
Checkout in the US	Yes	Through the store’s own checkout or brand apps in ChatGPT

ACP first powered ChatGPT Instant Checkout. OpenAI let that feature go in March 2026; stores now use their own checkout. How that works is in ChatGPT Instant Checkout.

Which store platforms support UCP?

• Shopify co-developed UCP and connects stores through Agentic Storefronts in the admin to ChatGPT, Microsoft Copilot, Google AI Mode and Gemini. According to the Shopify help page, it is on by default for eligible stores.
• Adobe Commerce (Magento) announced on February 18, 2026 that it will support UCP and ACP, without a concrete timeline.
• WooCommerce is working with Stripe on ACP according to an October 2025 post. A request for built-in UCP support has been open on the WooCommerce ideas board since January 2026, without an official response. Third-party plugins exist.

What should your store do with UCP now?

If you sell to US customers, UCP is live for you now, and the route depends on your platform. Whatever your platform, the foundation UCP builds on counts first:

1. A complete product feed in Google Merchant Center. According to Google, that is how your products are found in AI Mode and Gemini. Which fields matter is under product data every AI assistant needs.
2. Product descriptions that match how people ask. Google made “conversational attributes” available worldwide in Merchant Center in May 2026, for descriptions that fit conversational search.
3. Product pages a crawler can read. Price, stock and specs as plain HTML text, with Product structured data that matches what the visitor sees. The technical scan shows what is in the HTML of your pages.
4. On Shopify: check Agentic Storefronts. The connection comes with the platform; make sure the channels you want are on.
5. On WooCommerce or Magento: follow your platform. Prefer support from the platform itself over a separate integration you have to maintain, or consider Shopify’s Agentic plan for AI-channel sales.

Whether AI assistants already name your store does not depend on UCP but on your content and product data. GreatCompany will measure every day whether ChatGPT and other AI models name your business; join the waitlist for early access.

What is still on the roadmap?

Google and the UCP specification name these next steps:

• More countries: Canada and Australia within months after May 2026, then the United Kingdom.
• More sectors: Google is extending UCP to lodging and food. At Google Marketing Live it announced hotel booking in AI Mode and food ordering through Google Maps.
• After the purchase: tracking and returns in Google’s AI channels.
• Buy now, pay later: Affirm and Klarna in Google Pay.

Read on

• Agentic commerce for Shopify, WooCommerce and Magento
• ChatGPT Instant Checkout: what it was and what changed
• How AI crawlers read your site
• JSON-LD and schema markup