- [Openmeetings](https://openmeetings.apache.org/index.html) - Openmeetings provides video conferencing, instant messaging, white board, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming. ([Source Code](https://openmeetings.apache.org/source-repository.html)) `Apache-2.0``Java`
- [Openmeetings](https://openmeetings.apache.org/index.html) - Openmeetings provides video conferencing, instant messaging, white board, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming. ([Source Code](https://openmeetings.apache.org/source-repository.html)) `Apache-2.0``Java`
- [Sogo](http://www.sogo.nu/) - SOGo offers multiple ways to access the calendaring and messaging data. CalDAV, CardDAV, GroupDAV, as well as ActiveSync, including native Outlook compatibility and web interface. ([Demo](http://demo.sogo.nu/SOGo/), [Source Code](https://github.com/inverse-inc/sogo)) `GPLv1/LGPLv2``Objective-C`
- [Sogo](http://www.sogo.nu/) - SOGo offers multiple ways to access the calendaring and messaging data. CalDAV, CardDAV, GroupDAV, as well as ActiveSync, including native Outlook compatibility and web interface. ([Demo](http://demo.sogo.nu/SOGo/), [Source Code](https://github.com/inverse-inc/sogo)) `GPLv1/LGPLv2``Objective-C`
- [Zimbra Collaboration](https://www.zimbra.com/downloads/) - Email, calendar, collaboration server with web interface and lots of integrations. ([Source Code](https://git.zimbra.com/repos/zimbra-foss/)) `GPLv2/CPALv1``Java`
- [Zimbra Collaboration](https://www.zimbra.com/) - Email, calendar, collaboration server with Web interface and lots of integrations. ([Source Code](https://github.com/zimbra)) `GPL-2.0/CPAL-1.0``Java`