Open Source Intranet Software
An intranet is where a company keeps the knowledge it would never put outside the firewall - org charts, internal docs, the half-private conversations that run the place - which makes hosting it on someone else's cloud a strange bet for the most sensitive collaboration you do. The open source portals here bring wikis, social feeds, and team spaces together on a server inside your own network, so the internal life of the company stays on infrastructure your own IT actually controls.

HumHub
Open source intranet and community software for communication, collaboration, and shared content

Twake
Privacy-first open source digital workplace for chat, files, calendar, tasks, and documents

Elgg
Open source PHP framework and CMS for building socially aware web applications