By James Calloway

Google has launched Universal Cart in the United States, letting shoppers build one cart across multiple retailers inside Google Search, AI Mode and the Gemini app, and check out with Google Pay or on the retailer's own site. Suresh Ganapathy, Senior Director of Product Management for Consumer Shopping, announced the rollout in a blog post. Google first previewed the feature at I/O in May.

The timing is deliberate: the cart lands before the holiday shopping season starts.

What does Universal Cart actually do?

Shoppers add products from several stores and keep everything in one cart across Search and Gemini. The cart sends alerts when a saved item drops in price or comes back in stock.

It's built on Google Wallet, so it can suggest which of a shopper's cards to use based on each card's perks, and it surfaces promo codes in the cart.

Google names Nike, Sephora, Target, Ulta Beauty, Walmart, Wayfair and many Shopify merchants for in-cart checkout or cart transfer. The merchant stays the seller of record either way.

What changed since the May I/O announcement?

In May, Google said it expected Search and Gemini in the U.S. to have the cart by end of Summer, with YouTube and Gmail to follow later. Today's post says nothing about YouTube or Gmail, and gives no timeline for either.

Several May features are also missing from the launch post:

• Historical pricing for items
• Warnings that products in your cart won't function together
• Loyalty program information tied to Google Wallet

They may have shipped, but the launch post doesn't describe them.

The framing shifted too. In May, Google called Universal Cart "the next step that brings this all together" for its agentic commerce foundation. Today's post splits agentic features that act on a shopper's behalf from tools that "give shoppers confidence and control," and places the cart in the second group.

How do carts reach merchants?

Google's developer docs tie cart transfer to the Cart API in the Universal Commerce Protocol (UCP). A CreateCart call builds a cart on the merchant's system when a shopper transfers items.

This first release is one-way. It covers cart creation and transfer only — no updating, deleting or syncing cart contents between Google and the merchant's system. Native checkout on Google runs on a separate API and isn't required for cart transfer.

Merchants that meet Google's onboarding requirements pick either option in the UCP integration hub in Merchant Center. Google says the hub is rolling out gradually in the U.S., with Australia and Canada to follow next year. Google added the hub's cart transfer option in September.

What can merchants measure?

The UCP Analytics Reporting dashboard in Merchant Center tracks the checkout funnel from Buy button clicks through purchases and cancellations. Google's Merchant API reference lists cart transfer metrics — number of transfers, average cart value at transfer — and calls each equivalent to a dashboard metric. That API reporting is in alpha. None of the pages list a metric for products saved to a cart.

UCP sales tracking counts transfers and purchases separately. The purchase count includes only completed purchases made directly from the Universal Cart list; purchases after a transfer happen on the merchant's site.

What's the Shopify catch?

Shopify's support docs say Direct Checkout is enabled by default for eligible U.S. Shopify stores via the Google AI Mode & Gemini Channel. But Google Analytics and Custom Pixels will not fire when a customer buys through Direct Checkout — a real attribution gap for merchants relying on their own analytics.

Shopify store owners can check whether Direct Checkout is on via Sales channels > Agentic in the Shopify Admin. No documentation covers how Universal Cart handles in-cart purchases from Shopify merchants, or whether they use the same checkout flow as Direct Checkout. SEJ contributor Slobodan Manic recently reported on those default settings.

The bottom line: a shopper's list now lives with their Google account, and Google sits between discovery and checkout. Merchants that get UCP hub access should watch buy clicks, purchases and cart transfers on the analytics tab — because that's where the holiday numbers will show up first.