WhatsApp now has a user base of more than one billion, but Telegram is quickly catching up. In February 2016 Telegram claimed over 350,000 users signed up every day, on top of the existing 100 million daily active users.
Telegram faces a lot of criticism for not being fully encrypted by default. But they were the first mass-market messaging app to offer any encryption, and as such were often referred to as the encrypted chat app in the media. Its a nickname that seems to have stuck, and one that might have even contributed to the endorsements garnered from groups such as the notorious terrorist group, ISIS.