UCP and Google Universal Cart explained

What is UCP (Universal Commerce Protocol)?

UCP is an open standard for how AI agents and online stores talk to each other when a customer wants to buy something. It was co-developed by Google and Shopify, announced at NRF in January 2026, and is open source on GitHub under the Apache 2.0 licence. According to Shopify it is also backed by Amazon, Meta, Microsoft, Stripe, Target, Walmart and Visa, among others.

Think of UCP as a shared language. Instead of every AI platform building its own integration with every store, the store describes itself once in a standard way. Any agent that understands UCP can then read what the store offers, and buy from it.

Why does agentic commerce need a shared protocol?

Without a standard, every store would have to connect to ChatGPT, Gemini, Copilot and Perplexity separately, and each connection would behave slightly differently. That doesn’t scale, for stores or for platforms.

UCP standardises the steps that always repeat: what the store can do, how a checkout is created and updated, and how payment is authorised. The store keeps control of its own rules for price, discounts and shipping.

How does UCP work, step by step?

Google has published a technical walkthrough, Under the Hood: Universal Commerce Protocol. Simplified, the flow looks like this:

1. The store publishes a manifest. A JSON file at /.well-known/ucp describes the services and capabilities the store supports, its endpoints, and the payment handlers it accepts.
2. The agent reads the manifest. There it finds, for example, the service dev.ucp.shopping and the capability dev.ucp.shopping.checkout, with extensions such as discount and fulfillment.
3. The agent creates a checkout session. With POST /checkout-sessions it sends line items, buyer, currency and the payment handlers it supports. The store replies with a status, for example ready_for_complete when everything is in place.
4. The session is updated along the way. Changes such as a delivery option or a discount code go through PUT /checkout-sessions/{id}. The store recalculates using its own rules.
5. Payment is authorised. UCP separates payment handlers (for example shop_pay or google_pay) from the payment instrument itself. Every authorisation is backed by cryptographic proof that the customer consented. The protocol is compatible with AP2, Google’s agent payments protocol.
6. The store completes the order. The order lands in the store’s own systems. The store is the merchant of record and owns its business logic.

Agents can talk to the store over plain REST, over MCP (Model Context Protocol) or over A2A (Agent2Agent), so the same setup works for different kinds of agents.

What is Google Universal Cart?

Universal Cart is Google’s cross-merchant shopping cart. It was previewed at Google I/O on 19 May 2026 and rolled out in the U.S. on 15 October 2026, across Google Search and the Gemini app. YouTube and Gmail are to follow.

Shoppers can add items from several stores to one cart. Google tracks price drops and price history, sends back-in-stock alerts, flags items that are incompatible, and applies Google Wallet perks and loyalty programmes. The shopper can check out with Google Pay in a few taps, or move the items to the merchant’s own site. Google says the brand stays the merchant of record either way.

Merchants Google names include Nike, Sephora, Target, Ulta Beauty, Walmart and Wayfair, plus Shopify merchants such as Fenty and Steve Madden (Digital Commerce 360).

How do UCP and Universal Cart fit together?

Universal Cart is what the shopper sees. UCP is the pipe the checkout runs through. When a shopper pays in Universal Cart, UCP creates the checkout session with the store, fetches the right price, shipping and discount, and returns an authorised payment.

Google says UCP-powered checkout will expand to Canada and Australia in the coming months, and later to the U.K.

What do UCP and Universal Cart mean for a Shopify store in Norway?

The short answer: Universal Cart is not here yet, but UCP is already part of Shopify.

• Universal Cart: live in the U.S. Nothing announced for Norway or the Nordics as of 17 October 2026.
• UCP in Shopify: Shopify’s MCP tools implement UCP across discovery, carts, checkout and order monitoring (Shopify). Shopify Catalog syndicates eligible products to AI platforms, and in Agentic Storefronts you switch AI channels on and off. Checkout is Shopify Checkout, and you are the merchant of record.
• Traffic today: Across five Shopify stores we run, ChatGPT sent about 3,400 visits in the last 90 days, converting at about 2.2%. Perplexity, Gemini and Copilot together sent fewer than 30. Google’s agent surfaces have not reached Norway yet.

For a Shopify store, the work is therefore less about the protocol itself and more about what the protocol carries: product data, price and stock per variant, and shipping and discount rules clear enough for an agent to calculate the right total without asking a human.

“Agents don’t search, they read. Make sure you have something worth reading.” Øyvind Haagensen, CCO at Scandicommerce, on stage at Handelskonferansen 2026.

New to the topic? Start with What is agentic commerce?

Frequently asked questions

How we help stores with this

We make sure your Shopify store has product data, policies and checkout rules that agents can read and calculate with, so you are ready when more surfaces open in the Nordics. Read more about how we work with agentic commerce.