Market research firm Juniper Research is predicting significant growth for Apple Pay, Samsung Pay, and Android Pay this year.

In a new report entitled Contactless Payments: NFC Handsets, Wearables & Payment Cards 2017-2021, the firm says that the number of users of such mPayment platform will reach beyond 100 million users in the first half of the year, and will exceed 150 million by the end of it. By 2021, they will collectively have more than 500 million users, Juniper Research predicts.

Apple Pay will lead the way. Juniper Research estimates that the platform had 45 million users last year, compared to Samsung Pay’s 18 million and Android Pay’s 12 million. By the end of this year, it forecasts that Apply Pay will have 86 million users, while Samsung Pay will have 34 million and Android Pay will have 24 million.

Meanwhile, PayPal, which has long dominated consumer e-commerce, will “rapidly deploy a portfolio of contactless payment and loyalty solutions that will allow it to compete effectively for market share,” according to a report synopsis from Juniper Research. Indeed, PayPal has already begun to wade into the mobile payments space, just as Apple Pay and Samsung Pay have made inroads into traditional web-based e-commerce.