Cloud chats and groups are encrypted between the client and the server, so that ISPs and other third-parties on the network cannot access data. Telegram provides optional end-to-end encrypted chats. Telegram's official components are open source, with the exception of the server which is closed-sourced and proprietary. There are also two official Telegram web twin apps, WebK and WebZ, and numerous unofficial clients that make use of Telegram's protocol.

Various client apps are available for Smart TV, desktop and mobile platforms including official apps for Android, iOS, Windows, macOS, and Linux (although registration requires an iOS or Android device and a working phone number). The servers of Telegram are distributed worldwide with five data centers in different parts of the world, while the operational center is based in Dubai, United Arab Emirates. It was launched for iOS on 14 August 2013 and Android on 20 October 2013. The application also provides optional end-to-end encrypted (popularly known as 'secret') chats and video calling, VoIP, file sharing and several other features. Telegram Messenger is a globally accessible freemium, cross-platform, encrypted, cloud-based and centralized instant messaging (IM) service.

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