An iPhone app launching today provides a glimpse into the future of shopping. Created by Modiv Media, the app lets customers scan items while they shop, presents them with personalized offers as they go, and speeds up their checkout. One of the first companies to deploy the app is Stop & Shop, which operates more than 375 supermarkets in the eastern United States.

Stop & Shop's version of the app, called Scan It!, relies heavily on loyalty-card numbers for its smarts. Users install the app, load in their loyalty card by capturing it with the phone's camera, and then take the phone to the store. The phone's camera captures the bar codes of items the person puts in a shopping cart and adds their prices to a running total. The user bags items while shopping, thus avoiding having to unload and reload the cart at the register. A store might sometimes have employees perform checks to make sure users are paying for everything in their carts, but for the most part it's an honor system.

The app uses data from the loyalty card to present offers based on the user's past purchases and current location in the store. It works in addition to the existing loyalty program, offering savings on top of the deals already advertised on store shelves.

When the user has finished shopping, the app sends information about the contents of the shopping cart to the store's point-of-sale system. The user can go to any register, scan the loyalty card, and pay for the order.

"The technology in the app puts you in control of the shopping experience," says John Caron, Modiv Media's senior vice president of marketing.