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

Tresorit is an online cloud storage service based in Switzerland and Hungary that emphasizes enhanced security and data encryption for Businesses.

Rocket.Chat free open source chat solution.

Blink is the best real-time communications client using the SIP protocol.

LAN Messenger is a instant messaging program designed for use within a single local area network (LAN).

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 cl…

HipChat is a web service for internal private online chat and instant messaging.

Qiscus provide everything you need to power up your app with chats.

Zulip is a chat and collaborative software.

Wickr is an instant messenger application.