Many of the Play Store install milestones that go by are more a reflection of 'how many phones was this app bundled with' than 'look at how many people downloaded this by choice.' Telegram doesn't ship pre-installed on any Android phones, but despite that, the app just passed 500 million downloads on the Google Play Store.

500 million is a far cry from WhatsApp's five billion installs or Google Messages' one billion installs, but unlike those two applications, Telegram has relied entirely on user downloads. That's quite an accomplishment, especially with the experimental Telegram X client having 10 million downloads on top of that.

Telegram
Telegram
Developer: Telegram FZ-LLC
Price: Free