Jan Koum, CEO and co-founder of WhatsApp, announced on Friday that the popular mobile messaging app now has 800 million monthly active users. Acquired by Facebook in 2014 for $22 billion, WhatsApp has the potential to reach one billion users this year. Since last August, the app has added 100 million active users about every four months. It now has more users than Facebook Messenger and competing apps. For many global users, the app has become an alternative to text messaging, and it recently added a feature for taking calls.

“Facebook now boasts about 1.4 billion monthly users, while its Messenger has about 600 million,” reports The Wall Street Journal. “Founder and CEO Mark Zuckerberg has previously said he expects WhatsApp to contribute to the company’s bottom line, but not until it reaches roughly a billion users.”

“What I’d say around messaging is we’re pretty early in that cycle,” said Zuckerberg. “We are about where Facebook was in around 2006 or 2007, where, at that point, Facebook is really just a consumer product. There were no businesses in the ecosystem.”

It is not clear how WhatsApp would be monetized, since Koum has expressed reluctance to feature ads on the service. However, its numbers give it a significant advantage over the competition.

“While the app has a raft of competitors — Tango, Viber, Line, Kik, BBM, and WeChat among them — none has a user base as big as WhatsApp’s,” notes Digital Trends. “And the speed at which it’s growing is certainly impressive. Facebook took around eight years to reach a billion users, while WhatsApp looks set to achieve the same feat in about six.”