Shoppers in the United States can now fill one Google cart from many retailers, and the route that cart takes to a merchant decides who captures the sale. Google switched on Universal Cart on October 15 across Search, including AI Mode, and the Gemini app, according to Search Engine Journal. The cart is shared between the two surfaces.
Our May 20 coverage covered the I/O announcement and what it meant for retail visibility. This update covers what actually shipped and how a cart reaches a store.
On the shopper side, the product tracks saved items and sends alerts when a price falls or stock returns. Google Wallet underpins the cart, which lets it recommend the card whose perks fit each purchase, and promo codes appear alongside the items. Google’s partner list leads with Walmart, Target, Nike, Sephora, Wayfair, and Ulta Beauty, and adds a large group of Shopify merchants. The retailer stays the seller of record under either checkout path.
Those two paths matter most. Native checkout completes the sale on Google, with Google Pay as an option. Cart transfer sends the shopper to the merchant’s website with a pre-filled cart. Per Google’s developer documentation, transfer runs through the Universal Commerce Protocol (UCP) and its Cart API, which has the merchant’s own system build a cart when a shopper sends items over, using a call named CreateCart.
The first release is deliberately narrow. The documentation says it handles creation and transfer only. Edits, deletions, and syncing of cart contents across the two systems are not supported. Native checkout is a separate API and is not a prerequisite for transfer. In practice, the cart a shopper built on Google and the cart that opens on the store are two separate objects once the handoff happens.
Merchants opt in using the UCP integration hub inside their Merchant Center account, provided they meet Google’s onboarding requirements. A Google support page describes the hub as reaching U.S. merchants in stages, and Australia and Canada are slated for next year.
Reporting is where the gaps show. The UCP Analytics Reporting dashboard traces the funnel from Buy button clicks to completed orders and cancellations. A separate Merchant API reference page adds cart transfer metrics, such as how many transfers occurred and the mean cart value when each one happened. The API version of this reporting is still an alpha release. Search Engine Journal found no documented metric for items a shopper merely saved. Purchases credited to Universal Cart cover sales finished from the cart itself, while sales that follow a transfer happen on the merchant’s own site.
Shopify merchants face an extra unknown. Shopify’s help documentation says eligible U.S. stores get Direct Checkout switched on automatically, and that neither Google Analytics nor Custom Pixels registers a purchase completed through it. Search Engine Journal could not establish how in-cart purchases from Shopify merchants are processed, or whether they follow the same flow as Direct Checkout.
Several May promises are absent from the launch post. In May, Google expected Search and Gemini to carry the cart before summer ended, with YouTube and Gmail to follow. The new post is silent on those two surfaces and gives no timeline. It also omits historical pricing, warnings that cart items will not work together, and Google Wallet loyalty details that appeared in May. Google now describes the cart as a tool that gives shoppers confidence and control, and places it apart from the agentic tools that take actions for the shopper. That framing is a change from May, when the cart was presented as the step that brings the agentic work together.
For retailers, the practical question is attribution. A saved item that never reaches a transfer leaves no trace in the reporting Google has documented, so demand created inside the cart can stay invisible until a shopper arrives.
Search and ecommerce teams should confirm hub access in Merchant Center now, decide between native checkout and cart transfer for each product line, and test whether transferred orders appear in their own analytics before holiday traffic arrives. Shopify stores should check the Agentic sales channel setting in the Shopify Admin first.
Search Engine Journal, Matt G. Southern, published October 15, 2026, with supporting detail from Search Engine Roundtable.
