Nextcloud

Nextcloud is the software behind your own private Dropbox, minus Dropbox. Install it on a home server, a Raspberry Pi, or a rented VPS, and it hands you file sync, calendars (CalDAV), contacts (CardDAV), and a growing Office suite for co-editing documents — all served from hardware you own. The core is PHP and Vue, AGPL-3.0 licensed, with 35,000+ GitHub stars and a release cadence that lands every few weeks. What makes it more than a file drop is the app store. Governments, universities, and companies like Deutsche Telekom bolt on video calls (Talk), kanban boards (Deck), and even a local AI assistant, turning the base install into something closer to an internal Google Workspace. Admins manage all of it through the occ command-line tool, and the official Docker image handles first-run setup through environment variables — set MYSQL_HOST and friends and skip the install wizard entirely. The honest caveat: performance is on you. Several self-hosters report a snappy first week that slows down once real usage kicks in, especially on underpowered hardware — a dual-core box with 4GB RAM will choke, while a quad-core with 8GB and an SSD runs fine. Nextcloud AIO exists specifically to take the sting out of that setup, but there's no getting around needing to actually run a server.