What Is the Universal Commerce Protocol (UCP)? A Guide for Ecommerce Brands

When a shopper asks Google's AI Mode or Gemini to find a product, they can increasingly buy it without visiting the retailer's website. The technology that makes that possible is the Universal Commerce Protocol, or UCP.

UCP is an open standard that lets AI agents work with online stores: finding products, building carts, checking out and handling what happens after the order. Google launched it in January 2026 with Shopify, and some of the biggest names in retail have signed on since.

If you sell online, there's a good chance your products are already eligible. Here's what UCP is, how it works, where it's live, and what it means for the relationship you have with your customers.

What is the Universal Commerce Protocol?

The Universal Commerce Protocol (UCP) is an open standard that defines how AI agents and online stores talk to each other. In Google's words, it's "a new open standard for agentic commerce that works across the entire shopping journey", from discovery and buying to post-purchase support.

Google CEO Sundar Pichai announced UCP at the National Retail Federation's Big Show on January 11, 2026. The specification is published at ucp.dev under the Apache 2.0 open source license, so anyone can build with it.

The problem it solves is one of scale. Before UCP, every AI shopping assistant needed its own custom connection to every retailer. With a shared standard, a store can describe what it supports once, and any compatible agent can work with it.

UCP is designed to sit alongside other AI protocols rather than replace them. Google says it's compatible with Agent2Agent (A2A), the Agent Payments Protocol (AP2) and the Model Context Protocol (MCP), which we compare later in this guide.

Who's behind UCP?

Google co-developed UCP with Shopify, and launched it with Etsy, Wayfair, Target and Walmart as co-developers. More than 20 other companies endorsed it at launch, including Adyen, American Express, Best Buy, Mastercard, Stripe, The Home Depot, Visa and Zalando.

Shopify's engineering team says UCP's checkout design grew out of Shopify's own Checkout Kit, the system it already uses to embed checkout in other apps.

The circle has widened since. In April 2026, Amazon, Meta, Microsoft, Stripe and Salesforce joined UCP's Tech Council, the group that approves changes to the specification.

Google and Shopify still hold the most influence. Under UCP's governance rules, each has a permanent seat on the five-member Governing Council, Google manages the ucp.dev domain, and Google holds the vote for any open council seats until December 2028.

How UCP works

You don't need to understand the technical details to benefit from UCP, but knowing the basic flow helps you see what an AI agent can and can't do with your store.

1. Your store publishes a profile. Each business that supports UCP publishes a machine-readable file at a standard address on its website (/.well-known/ucp). It lists what the store can do, such as checkout or loyalty, and which payment methods it accepts. Any compatible agent can read it without signing up first.

2. The agent and the store agree on what to use. When an agent connects, it shares its own profile. The store then works out which features both sides support and uses those.

3. The agent carries out the shopping task. UCP covers the main steps of a purchase:

4. Payment runs through your existing provider. UCP defines how a payment method, such as Google Pay, hands a secure token to your payment processor. You stay the merchant of record, and your processor charges the customer as usual. For future purchases where an agent buys without the shopper confirming each step, UCP can use Google's Agent Payments Protocol to prove what the shopper authorized.

The specification uses date-based versions. The latest, 2026-08-25, added support for loyalty programs and more payment security features, and Shopify storefronts support it automatically.

Where is UCP live today?

UCP's first and biggest use is checkout on Google. When a shopper finds an eligible product in AI Mode in Google Search or the Gemini app, they can buy it there, paying with the card and shipping details saved in their Google Wallet.

Rollout has moved quickly:

Availability outside the US is still arriving. Google's Merchant Center help page covers products eligible in the US, Canada and Australia, and notes that the checkout feature is available for select merchants. Shopify's integration is currently US-only.

Other platforms are building UCP into their software too. Salesforce has announced native UCP support for its Agentforce Commerce merchants, and Visa and Mastercard are among the payment networks that have endorsed it.

Does UCP affect your store?

That depends on how your store is built.

If you're on Shopify in the US, it probably already does. Shopify connects stores to Google's AI checkout through its Agentic Storefronts feature, and direct checkout is activated by default for eligible stores. To be eligible, your store must be based in and sell to the US, have a valid Google Merchant Center account and have its policies completed. Shopify says there are no extra fees beyond your standard payment processing.

Some products are excluded on Shopify, including subscriptions, product bundles, customizable products and B2B-only products. You can switch direct checkout off and send shoppers to your own store instead.

If you're on another platform, ask your provider. Some platforms are building UCP support, but timelines vary.

If you run a custom store, you can integrate directly. Google's developer guide offers two routes: a checkout path, where purchases complete on Google, or a cart path, where Google hands a filled cart to your website. Either way, Google must approve your integration before it goes live.

How to get your products UCP-ready

Whatever your platform, the groundwork is mostly about product data and policies:

• Keep Merchant Center in good standing. UCP checkout builds on your existing Google Merchant Center account and product feed.
• Opt products in. Google uses a feed attribute, native_commerce(checkout_eligibility), to mark products as eligible. It defaults to false, so products aren't included unless you, or your platform, turn it on.
• Check the exclusions. Subscriptions, installment plans, personalized goods such as engraved items, final-sale and used items, and pre-orders aren't eligible for checkout on Google.
• Publish clear policies. You'll need a return policy and a customer support contact, and shoppers will rely on them because they never visit your site.
• Keep prices and stock accurate. Agents check live pricing and inventory, and errors become failed or cancelled orders.
• Accept Google Pay. Google's US terms require Google Pay for UCP checkout, so your payment processor needs to support it.

What UCP means for customer relationships

For a retention-focused brand, the most important question is who owns the customer when the sale happens inside Google.

The good news is that you stay the merchant of record. Google tells merchants they can "keep all of your customer data and relationships", and you fulfill the order, handle returns and provide customer service.

There are limits, though:

• Email marketing needs consent. Under Google's US terms, the shopper's email address can't be used for marketing emails unless they've opted in. You'll get their details for the order, but not automatically a subscriber.
• Your tracking won't see the checkout. Shopify notes that Google Analytics and custom pixels don't fire in Google's direct checkout, so these orders won't look like normal web conversions in your analytics.
• The first impression isn't yours. The shopper sees your product inside Google's interface, not your site, your brand story or your upsells.

That makes the moments you do control more important. The delivery experience, the packaging, the first post-purchase email and an easy way to join your loyalty program all carry more weight when the first purchase happened somewhere else. Identity linking helps here: if a shopper connects their account, your member pricing and loyalty benefits can follow them into Google's checkout.

UCP vs ACP, AP2, MCP and A2A

UCP is one of several new protocols for AI agents. Some do similar jobs, while others work alongside it:

The main rival is ACP. OpenAI originally used it for Instant Checkout inside ChatGPT, but in March 2026 it changed course, letting merchants use their own checkout experiences while it focuses on product discovery. For brands on major ecommerce platforms, support for both is likely to come through the platform rather than through their own development work.

Concerns and open questions

UCP is young, and a few questions are still open.

Pricing. Shortly after launch, Lindsay Owens, executive director of the consumer economics think tank Groundwork Collaborative, warned that Google's plans could allow personalized upselling based on shoppers' chat data. Google responded that it prohibits merchants from showing higher prices on Google than on their own sites.

Control. UCP is open source, but Google and Shopify hold permanent governance seats, and Google controls the vote for open seats until 2028.

Fit for DTC brands. Many direct-to-consumer staples, such as subscriptions, bundles and personalized products, aren't eligible for checkout on Google yet.

Measurement. With pixels and analytics not firing in Google's checkout, brands will need new ways to attribute and compare these sales.

Final thoughts

UCP turns Google's AI shopping surfaces into a place where customers can actually buy, not just browse. For many brands, especially on Shopify, it's already switched on.

The practical steps are simple: keep your product data and policies accurate, decide which products you want sold through AI checkout, and plan how you'll turn an order placed inside Google into a lasting customer relationship. Our guide to agentic commerce covers the bigger picture, and our AI in ecommerce statistics show how quickly shoppers are adopting these tools.