Telegram is a cloud-based instant messaging and voice over IP service. Telegram client apps are available for Android, iOS, Windows Phone, Windows, macOS and GNU/Linux. Users can send messages and exchange photos, videos, stickers, audio and files of any type.
Telegram’s client-side code is free software, whereas its server-side code is closed-source and proprietary. The service also provides APIs to independent developers. As of April 2020, Telegram had 400 million monthly active users. An announcement at that time included a promise to implement secure group video calls later in 2020