Google launched Universal Cart in the United States on October 15, rolling out across Google Search and the Gemini app a shopping cart it first previewed at I/O in May. Shoppers can save products from multiple retailers into one cart and pick the list back up on another Google surface.

The cart watches saved items in the background and notifies shoppers when a price drops or an out-of-stock item returns. It can also surface promo codes and weigh credit-card perks held in Google Wallet when suggesting how to pay.

Checkout runs through Google's Universal Commerce Protocol. At some large retailers shoppers can pay inside the cart with Google Pay; at others the cart hands off to the merchant's own site, so the experience is not yet uniform. Google is pitching the launch as a holiday-shopping tool.