Fresh from announcing it had hit 350 million monthly active users (MAU) back in October, we noted that WhatsApp may be leading the mobile messaging battle, but was it really capable of winning the war?

Well, the company has just announced another major milestone – it’s now drawing in 400 million users each month. That’s quite a jump up from just two months ago – 50 million new users in two months, and 100 million new users in the past four months. Not bad for a company consisting of just fifty employees.

The actual number of people who have downloaded the app and used it, however, will be more. But by using the MAU metric, this attempts to give more meaning to such data, given that it considers actual regular use.

WhatsApp Blog | 400 Million Stories