About 500 Walmart and Kroger stores this year will utilize a smartphone app that eliminates the need for customers to interact with cashiers, according to published reports. Both companies are already using the technology, but plan to expand it in 2018.

Walmart announced this week that 100 more stores will use its "Scan & Go" app. Walmart is already testing Scan & Go in a few select markets, including Texas, Florida, South Dakota, Arkansas, Georgia and Kentucky, according to Business Insider. Two-hundred Walmart stores will have the technology by the end of 2018, reports state.

How does it work?

Customers use the app to scan and bag items while they shop. The app displays the cost of each item, along with a running total. When customers are finished shopping, they can pay directly from their phones instead of standing in line at a register. Before leaving the store, Scan & Go customers will walk through a Mobile Express lane for security purposes.

Some of the test stores have Scan & Go kiosks that allows customers to try out the system on a store handheld device before downloading the app to their phones.

The Kroger grocery store chain is using a similar technology called "Scan, Bag, Go." Four hundred stores are expected to be using it by later this year, CNBC reported. At Kroger, shoppers can use either a phone app or a hand-held scanner provided by the store, Business Insider reported.

The technology will keep a running tab of shoppers' purchases, and will automatically offer any applicable coupons, according to Business Insider. Kroger's app will eventually feature the ability to alert shoppers when they walk by an item that is on their shopping list. When they are done shopping, customers will head to a self-checkout register to pay. Similar to Walmart, Kroger will eventually offer shoppers the ability to pay directly from their phones.

What are the advantages?

The shopping apps can allow allow customers to pass through stores more quickly. But stores are also looking for ways to cut costs and increase the bottom line. Often, cutting employees is the only way to save costs. Stores also have the option of transferring cashiers into other positions.