Google Lets UCP Merchants Send Shoppers to Their Own Carts

Google has added cart transfer to the Universal Commerce Protocol (UCP) integration hub in Merchant Center, so merchants can pass a shopper’s cart from Google to their own site to finish the purchase. The hub also gains enhanced checkout flow testing, and Google says analytics and more are coming soon.

Google announced the changes on 16 September in a holiday shopping update. The new capabilities are rolling out gradually in the US, with Australia and Canada to follow early next year.

What UCP Is

UCP is Google’s open protocol for agentic checkout, which lets shoppers buy products directly in Google’s AI shopping surfaces. The Keyword covered the first checkout rollout in AI Mode and Gemini in February, the expansion to main Search results in May and UCP checkout in YouTube Shopping ads later that month. Retailers remain the merchant of record for these orders.

Google says UCP already enables direct checkout for hundreds of thousands of brands and retailers across its surfaces. The integration hub is where merchants set it up, after Google opened self-service onboarding in Merchant Center in April.

What Cart Transfer Changes

Until now, UCP checkout meant the purchase was completed on Google. Cart transfer gives merchants who use the hub a second option: the shopper builds a cart on Google and is then passed to the merchant’s own site to complete it.

That matters to retailers who want to appear in AI shopping answers without handing over the final step of the sale. On their own site they keep their checkout design, upsells and account sign-ups, along with the first-party data that comes with them.

It also changes how AI-driven sales are measured. An order completed on the retailer’s site runs through the retailer’s own analytics and attribution. An order completed on Google arrives with whatever reporting Google provides, which is why the promised analytics matter to merchants who keep checkout on Google.

Google has not detailed what the enhanced checkout flow testing covers. Both point at the same need: merchants want to see how agentic checkout performs before they rely on it during the busiest weeks of the year.

Google’s UCP developer documentation, last updated on 3 September, already describes a UCP Analytics Reporting dashboard under Settings > UCP Integration in Merchant Center, available to all UCP-enabled merchants with the Performance role, reporting clicks to buy, purchases, purchase rate, average order value, cancellations, account linking and top-selling UCP products.

Retailers Already on UCP

Google gave Tapestry as an example. The owner of Coach and Kate Spade integrated UCP-powered checkout and now sells in Search, including AI Mode, and in the Gemini app ahead of the gifting season.

A Contest for Merchants’ Checkouts

The rival AI platforms are courting the same merchants. OpenAI runs its own checkout protocol in ChatGPT, a race The Keyword examined in February. This week The Wall Street Journal reported that Shopify will let Meta’s Muse agent check out on its stores using Shop Pay.

Each platform is trying to make it cheap for merchants to accept purchases inside its assistant. Cart transfer lowers the price of joining Google’s version. A retailer that was unwilling to let Google run its checkout can now take the traffic from AI answers and still close the sale on its own terms.