Telegram is a cross-platform cloud-based instant messaging, video calling, and VoIP service. It was initially launched for iOS on 14 August 2013 in Russia, and is currently based in Dubai. Official Telegram client apps are available for Android, iOS, Windows, macOS and GNU/Linux, as well as for the now-discontinued Windows Phone. There is also an official web interface and numerous unofficial clients. All of Telegram's official apps are open source.