Nextcloud

Syncthing is an open source peer-to-peer file synchronisation tool.

Web-based operating system designed to be feature-rich, exceptionally fast, and highly extensible.

File hosting and sharing solution primary for teams and organizations.

All-in-one solution for saving, synchronizing, viewing, editing and sharing files, calendars, address books and more.

Unison is a file-synchronization tool for OSX, Unix, and Windows.

Minimalist JSON storage service with synchronisation and sharing abilities.

Turn any web server into a powerful file management system and an alternative to mainstream cloud storage providers.

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.

Video conferencing, instant messaging, whiteboard, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming.

File sharing + sync, notes, and photos (alternative to Nextcloud and ownCloud's RSS reader).

Software suite including calendars, address books, notepad, project management tools, client relationship management tools (CRM), knowledge management tools, a wiki and a CMS.