Nextcloud provides a web interface, iOS app, Android app, and desktop client available for continuous file synchronization and active collaboration between users.
Documents can be collaborated on in real time with other users. Files and folders can be shared with read and/or edit privileges to specific users, email addresses, by link with optional password, expiration date, or note. Built in version control ensures mistakes can be undone and you have access to document history.
Workflows allow for task automation, including processes that can automate file conversions, document approvals, enforcement of retention polices, analytics which utilize 3rd party data, etc.
Nextcloud is extensible. With it's own app store, you're able to browse and install 3rd party applications, or build your own to extend its functionality.
The 'docx' edit screenshot above illustrates the embedded document editing web interface functionality, including such actions as reviewing history, embedded collaboration through Chat, tracking Comments, and Sharing to internal and external persons/groups.