Wal-Mart Stores Inc. is upping the ante on price matching. The world's largest retailer said Wednesday that it's expanding its online tool that compares prices on thousands of products with those of some of its competitors to cities nationwide in the next few months. It also plans to offer thousands more products, from general merchandise like TVs and shirts to veggies and other produce, on the online tool that's called Savings Catcher. And customers will also now be able to use Savings Catcher on Wal-Mart's mobile Relevant Products/Services app.

Wal-Mart rolled out Savings Catcher in seven markets in March, allowing customers to go to Walmart.com and compare prices of 80,000 grocery and household products at Wal-Mart with many of its competitors with physical stores. If the tool finds a lower price elsewhere, it refunds the difference to shoppers in the form of a store credit.

The discount behemoth is the latest retailer to aggressively court customers with a price-matching policy. Other stores, including Target and best Buy, offer to match the lower prices of competitors. But those programs only offer to match competitors' lower prices if shoppers do the research on their own, while Savings Catcher is designed to do the legwork for customers.

Wal-Mart move comes as it struggles to regain its footing as rivals push to beat its lower prices. The company built its business Relevant Products/Services on offering the lowest prices on staples such as milk, bread and laundry detergent. But its "every day low price" model is under attack Relevant Products/Services from dollar stores and grocery stores like Kroger in addition to online retailers like Amazon. On top of that, the retailer's primarily lower-income customers continue to struggle to stretch their money in a still tough economy.

Wal-Mart's U.S. discount division has recorded five consecutive quarter of declines in revenue at stores opened at least a year, a critical yardstick for measuring a retailer's health. The discounter also has seen a decline in the number of shoppers going to its stores for sixth straight quarters.

"Savings Catcher is a brilliant move on Wal-Mart's front to combat dollar stores," said Cameron Smith, who heads up a leading recruiting firm called Cameron Smith & Associates that hires executives for suppliers of Wal-Mart. "This is what Wal-Mart should be doing -- throwing down the gauntlet once and for all that they will not be beat on price."

Wal-Mart has had a price-matching strategy for several years. In 2011, it simplified the policy by making sure workers have the advertised prices of competitors on hand at the register, eliminating the need for shoppers to bring in an ad from a rival store. But unlike rivals like Target and Best Buy, Wal-Mart's policy does not match the prices of online rivals. The tool also excludes online rivals, along with store brand items, deli products, bakery and weighed items like produce and meat.

Wal-Mart says since it rolled out the savings tool in March in Charlotte, North Carolina, Huntsville, Alabama, Minneapolis, Lexington, Kentucky., Dallas, San Diego and Atlanta, nearly one million receipts have been processed using Savings Catcher.

Here's how the tool works: A customer Relevant Products/Services has to set up an online account, log onto the Savings Catcher and type in the number on their receipt. Savings Catcher compares prices of every item on the receipt to a database of advertised prices of competitors that's provided by an undisclosed third party. Wal-Mart prices are matched to stores based on geographic location. Rivals include Dollar General, Target and Kroger.

Any difference in price is put on a Wal-Mart online gift card. Customers can accumulate savings or use the credit immediately.