Just how big can Facebook's Messenger app get? Try 800 million monthly active users and counting.
The social-networking giant said Thursday its mobile messaging app crossed that mark near year's end. That means the app added 100 million new users worldwide since June.
Messenger was the quickest growing app in the US in 2015 with a 31 percent increase in users year over year, according to Nielsen ratings.
"We are growing very, very fast, and it's all shaping up into thinking about what we can make this year better than last year," said Stan Chudnovsky, head of product for the Menlo Park, California-based company's messaging efforts.
Facebook is constantly seeking ways to broaden its services to keep its 1.55 billion users coming back, including with Messenger. Last year, the messaging app began partnering with app makers, including entertainment app Giphy. Other new features, including the M concierge service still in the testing phase, are designed to let Messenger compete with digital assistants like Apple's Siri and Google Now. Messenger is also teaming up with ride-hailing app Uber to get people across town.
For 2016, the Messenger team is working on new concepts, Chudnovsky said. For example, Messenger now lets people make video and voice calls without requiring a phone number or even being Facebook "friends." "All you need is just a name as Messenger provides that capability to find anybody by name or the name of a business," he said.
The team is also developing ways to help people interact with more businesses through Messenger threads.
"We believe we have so much more opportunity ahead of us," David Marcus, Facebook's vice president of messaging products, said in a statement. "These are the early days of Messenger."
Messenger was built into Facebook in 2008 and later spun off into a separate app for mobile devices. In mid-2014, Facebook began requiring its users to download the app, which led to its growth spurt.