Telegram

Telegram is a messaging app that focuses on “speed and security” and describes itself as “like SMS and email combined”. Telegram’s product is a cloud-based messaging platform that allows users to share messages, photos, videos, and files, with conversations synced across all of a user's devices at the same time. Users can create groups of up to 200K people in size. Telegram also offers privacy features such as end-to-end encrypted device-specific secret chats, as well as end-to-end encryption for voice or video calls. Group or private chats not employing the “secret chat” feature are not end-to-end encrypted, but instead protected by what Telegram describes as server-client encryption.