Yes that was insane. Exactly one year before Whatsapp sold to Facebook for 19 billion dollars, that is in February 2013, they had about 200 million active users

Yes that was insane. Exactly one year before Whatsapp sold to Facebook for 19 billion dollars, that is in February 2013, they had about 200 million active users and 50 staff members. And not all of those staff members were developers I imagine.