WhatsApp has experienced tremendous growth since the time Facebook acquired it in 2014 for $19 billion.
Jan Koum, founder of the app, has just announced on Facebook that the service has reached 900 million monthly active users (MAU).
That means WhatsApp has gained 100 million new users in less than five months - Koum only celebrated reaching 800 million subscribers in April.
In comparison, Facebook's own Messenger app reached 700 million MAUs in June, mostly thanks to its split from the social network's main application.
When you consider that the app has been installed at least a billion times on Android alone, the new user count isn't that surprising.
