NEW YORK — The “Every Day Low Price” king is trying to shake up the world of pricing once again.

Walmart told The Associated Press that it has rolled out an online tool that compares its prices on 80,000 food and household products – from canned beans to dishwashing soap – with those of its competitors. If a lower price is found elsewhere, the discounter will refund the difference to shoppers in the form of a store credit.

The world’s largest retailer began offering the feature, called Savings Catcher, on its website late last month in seven big markets that include Dallas, San Diego and Atlanta. The tool compares advertised prices at retailers with physical stores, and not at online rivals like Amazon.com that also offer low prices on staples.

The move by Walmart, which has a long history of undercutting competitors, could not only change the way people shop, but also how other retailers price their merchandise. After all, Americans already increasingly are searching for the lowest prices on their tablets and smartphones while in checkout aisles.

Shoppers do this so often that big retailers that include behemoths like Target and Best Buy have started offering to match the lower prices of rivals – but only if shoppers do the research on their own. The idea behind Walmart’s online feature, on the other hand, is to do the legwork for customers.

Citibank launched a similar program two years ago that sends Citi credit card customers a check for the difference if Citibank finds a lower price from an online retailer. But Walmart is the first traditional retailer to offer such a program, and if it’s successful, others may follow.

Ken Perkins, president of retail research firm Retail Metrics LLC, said the move will “put pressure on everyone else to follow suit.” But he and other industry watchers voiced concerns that the tool doesn’t compare prices of online retailers.

After sending queries to some of Walmart’s competitors, it wasn’t clear Friday afternoon whether they planned to follow the move. And Walmart did not immediately answer questions about why it does not compare online prices.

Walmart’s U.S. discount division recorded its fourth consecutive quarter of declines in revenue at stores opened at least a year, a critical yardstick for measuring a retailer’s health.

For the new tool, a customer has to set up an account on www.walmart.com, log onto the Savings Catcher page 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. The tool doesn’t apply to general merchandise like clothing or electronic gadgets.

Walmart prices are matched to stores based on geographic location. Any difference in prices is put on a Walmart online gift card. Customers can accumulate savings or use the credit immediately.