Open Source Alternatives to Telegram

Switching from Telegram to an open source alternative mainly addresses two gaps: Telegram’s server is closed source even though its clients are open, and regular Telegram chats aren’t end-to-end encrypted by default — only opt-in Secret Chats are. Signal closes both gaps, with an open source server as well as client, and encryption enabled automatically on every chat, call, and group with nothing to opt into. Session takes a different approach, requiring no phone number at all and routing messages through a decentralized onion-routing network instead of any central server, Telegram’s or otherwise. What neither replaces is Telegram’s scale: large public channels with unlimited subscribers, groups up to 200,000 members, and an extensive bot API, none of which Signal or Session are built for. Someone using Telegram mainly for private one-to-one and small-group chat loses little by switching; someone relying on it for large communities or bot-driven automation will find neither alternative a full substitute.