Walmart now has an app that says its prices really are the lowest.

The discount giant has launched a web and mobile app that compares prices at rival stores and, if a competitor's price is lower, gives shoppers electronic gift cards for the difference.

Walmart calls it the Savings Catcher. Here's how it works:

-Go to www.walmart.com/savingscatcher or the Walmart app.

-Enter the receipt number  at the bottom of your Walmart receipt.

-Enter the date of the shopping trip.

Savings Catcher will look at the eligible items bought at Walmart, then compare prices to advertised prices in weekly print ads of major retailers such as Aldi, Harris-Teeter, Target and Walgreen.

If the app finds a lower price for the same item, customers will get a Walmart eGift card for the difference.

The retailer says it is using proprietary technology for the app, available on Walmart's mobile app or at Walmart.com

It will compare about 80,000 grocery and consumables items. Produce and general merchandise will be added in coming months.

"Our customers are savvier than ever when it comes to finding the best deals – they are using technology to do their research and spending hours clipping coupons," said Duncan Mac Naughton, chief merchandising and marketing officer of Walmart U.S. "We knew there had to be an easier way. It brings greater price transparency to the market and gives our customers confidence that they are finding some of the best deals available in retail."

Walmart launched the app as a pilot program in seven markets before going national earlier this month. The discounter said nearly 1 million receipts have been processed using the tool.

And it's likely to become even more advanced. Walmart promises a time when customers can instantly load an eReceipt into the tool.

"We are going to win by integrating digital and physical," Mac Naughton said."We are well-positioned to innovate and lead in the tech space."

lorraine.mirabella@baltsun.com