WhatsApp’s CEO, Jan Koum revealed in a blog post.
Its not a count of people who just registered for WhatsApp – it’s the number of people who are actively using the service every single month.WhatsApp has reached a milestone that no other mobile messaging service has achieved: 400 million monthly active users, with 100 million active users added in the last four months alone.”This is perhaps the most important stat when you look at social sites or messaging apps because it shows the number of people that really use the service. Other competitors of WhatsApp like Japan’s LINE and China’s WeChat which boast of 300 million and 270 million registered users respectively have not revealed their monthly active user data.
The figure represents a higher number of active users than social network Twitter which has about 232 million monthly active users.
WhatsApp makes its messaging app free for the first year and only charge $0.99 per year afterwards. This is its main source of revenue as it doesn’t put ads in its messaging app. It is also very interesting that WhatsApp only has 50 employees despite its popularity.