Rocket.Chat

Self-hosted team chat with voice, video, and omnichannel support

Cinny

Elegant open source Matrix client for self-hosted chat

Twake

Open source digital workplace with chat, files, and video calls

Converse.js

Self-hosted web-based XMPP chat client for any server

Element

Secure team chat built on the Matrix open protocol

Zulip

Organized team chat with threaded conversations, self-hostable

Mattermost

Team messaging for security-sensitive teams with air-gap support

Huly

One open source workspace to replace Jira, Slack, and Notion

Wire

End-to-end encrypted messaging, voice, and file sharing