Apple Pay lets users store credit and debit card information to a “mobile wallet.” Customers can then use their iPhone or Apple Watch to pay at retail stores that have point-of-sale registers equipped with near field communication technology, known as NFC. People can also use their Apple Pay accounts to pay for items within apps. Apple Pay has been integrated within thousands of apps, including Best Buy, Etsy, Sephora, Staples, Starbucks, Instacart, OpenTable, and Target.

The service is currently available in the U.S., U.K., Canada, China, and Australia. Apple said it would soon be introduced in Switzerland, Hong Kong and France, said Craig Federighi, Apple’s senior vice president of software engineering, said on Monday.

Web users will now see an Apple Pay button at participating retailers when they pay for items at checkout. When they choose to pay via Apple Pay on a Safari website, they will see a prompt on the webpage that will ask them to authenticate the payment. Users will then receive a prompt on their phone to authenticate the payment by pressing their finger on the touchpad via Touch ID.

Apple said an undisclosed number of online retailers have already committed to integrating Apple Pay on their websites, including Toys R Us and Etsy.

Making Apple Pay available on the web potentially expands the service’s reach to far more transactions. The service saves people from the hassle of having to re-enter credit card and billing information manually at checkout. Of course, Apple Pay will compete directly with PayPal, as well as the digital wallets from credit card giants American Express, Visa and MasterCard, along with e-commerce giant Amazon (AMZN).

Apple hasn’t released much information about how many people use Apple Pay. Rival PayPal says it has 184 million active users worldwide.

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Here’s what we do know about use of Apple pay. The service adds one million new users each week, Apple has said. However, the company failed to disclose the number of overall users, making it difficult to know if the users it does add remain loyal. Apple also said that transaction volume through Apple Pay is five times the amount from a year ago. Again, without a baseline, it’s impossible know whether the current volume is significant.

According to a recent report from Crone Consulting, Apple Pay has 12 million people users while rival services like Google’s Android Pay and Samsung Pay are tied for second place with 5 million users.