Discord Alternatives for Linux

Telegram is a free cloud-based instant messaging platform.

Slack is a cloud-based team collaboration tool.

Mumble is an open source, low-latency, high quality voice chat software primarily intended for use while gaming.

Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption.

TeamSpeak is software for quality voice communication via the Internet.

RetroShare is open source software for encrypted filesharing, serverless email, instant messaging, online chat, and BBS, based on a friend-to-friend network built on GNU Privacy Guard (GPG).

Mattermost is an open source, private cloud Slack-alternative, Workplace messaging for web, PCs and phones. MIT-licensed.

Wire is a cross-platform, encrypted instant messaging client created by Wire Swiss. It is available for iOS, Android, Linux, Windows, macOS and Web browser clients.

Ring (SFLphone) is an open-source SIP-compatible softphone and instant messenger for Linux, Microsoft Windows, OS X and Android.

Matrix is an open protocol for real-time communication. It is designed to allow users with accounts at one communications service provider to communicate with users of a different service provider via online chat, Voice over IP, and Videotelephony.

Zulip is a chat and collaborative software.

Dialog Messenger is a handy and feature-rich enterprise multi-device messenger available for server or cloud.

Wickr is an instant messenger application.