BENTONVILLE, Ark. – Walmart this month started testing Walmart Pay, its own mobile payment system, at locations around its headquarters in Bentonville, Ark., the New York Times reports. The discount retailer joins Apple, Samsung and Google in the mobile payment market. Walmart hasn’t accepted other mobile payment options in its stores.

The company plans to roll out the service to all of its 4,600 U.S. stores early in 2016. “Soon, customers can leave only with their keys and smartphone to shop at their local Walmart,” said Neil Ashe, head of e-commerce for Walmart. “It’s fast, easy and secure.”

Built on QR code technology, Walmart Pay is seen as a way to connect the company’s e-commerce with its in-store experience. The retailer is hoping that its customers will embrace the mobile payment system more than consumers have flocked to Apple Pay or Android Pay, both of which have found it difficult to persuade shoppers to use the payment apps.

“When Apple released Apple Pay, the idea was that we’re now moving forward with [near field communication], and that’s the way all mobile payments will be transacted,” said James Wester, a global payments expert at IDC Financial Insights. “But now, we’re beginning to see that no, that’s probably not the way it’s going to develop, and it’s not something we’re just going to give over to Apple or Google. Nobody’s won yet. So at this point, it’s still anybody’s game.”