WhatsApp CEO Jan Koum announced Monday that the cross-platform mobile-messaging app now has 430 million active users. That's up from 200 million in April 2013, which means its user base has more than doubled in less than a year.

The number of messages sent and received via WhatsApp has increased, as well, from 20 billion per day to 50 billion per day.

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Private messaging is becoming increasingly popular of late, especially for social networks such as Twitter, Facebook, Instagram and Snapchat — and yet, it seems WhatsApp continues to hold its own.

Statista's chart, below, shows the progression of WhatsApp's active user base and daily-message volume over the past 10 months.