Walmart and Dunkin’ Donuts Gaining on Apple Pay and Samsung Pay, But Starbucks Is Tops

Apple, Google, and Samsung have spent the past few years fighting to convince smartphone users to adopt their mobile payments systems.

But all the while, it’s coffee retailer Starbucks that had created the most popular mobile pay system, research firm eMarketer says. The Starbucks (sbux) payments app was used by 20.7 million people at least once every six months last year, beating out the 19.9 million Apple Pay users.

Google Pay was used by 9.3 million and Samsung Pay came in fourth place with 8.4 million users, despite being accepted in the most places, eMarketer said in a report released on Tuesday. Overall, 48 million people used one or more of the mobile pay apps last year, which is expected to jump to almost 15% to 55 million this year.

Mobile payments apps are finally starting to take off after years of hype. Increasing rewards available for paying with a phone combined with the introduction of EMV chip credit cards, which have slowed check out times for regular credit card users, are contributing to the growth.

The key to Starbucks popularity is the app’s links to the company’s rewards program, according to eMarketer analyst Cindy Liu. “For users of the app, the value of paying with their smartphone is clear and simple—you can save time and money at the register, all while racking up rewards and special offers,” Liu wrote in the report.

But while the three major smartphone makers’ apps will continue to grow, apps from other retailers are nipping at their heels. Apple’s (aapl) service will reach 27.5 million users by 2022, eMarketer forecast, compared to 14.9 million for Google (googl) and 13.2 million for Samsung. Starbucks will remain in first place in 2022 with a projected 29.8 million users.

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Among other retailers likely to gain ground, eMarketer pointed to Walmart (wmt), which launched its payments-capable app in 2015, McDonald’s (mcd) and Dunkin’ Donuts (dnkn). Target’s (tgt) payments app from last year is also a likely winner, the research firm said.

“Retailers are increasingly creating their own payment apps, which allow them to capture valuable data about their users,” Liu said. “They can also build in rewards and perks to boost customer loyalty.”