Short version: Nextcloud if you want Drive plus Docs, Seafile if you only need fast file sync, Syncthing if you just want your devices in step without a server. Stars, licences and maintenance status are from the GitHub API on 18 September 2026, which is how we know one popular option is now archived.

Nextcloud: the full suite
Nextcloud (about 37,000 stars, AGPL-3.0) covers files, sharing, calendars, contacts and collaborative documents through add-ons. The most complete replacement for Google Workspace, and the most maintenance.
Seafile: fast, focused sync
Seafile (about 15,000 stars) does file sync and sharing and does it efficiently, including large libraries with many small files. Lighter to run than Nextcloud.
Syncthing: no server at all
Syncthing (about 89,000 stars, MPL-2.0) syncs folders directly between your devices, peer to peer. No account, no central server, no web interface.
Also worth knowing
**ownCloud Infinite Scale** (owncloud/ocis, Apache-2.0) is a newer, Go-based rewrite of ownCloud for file sync and sharing. For moving files between nearby devices, LocalSend is the simplest option.
One to avoid
File Browser was archived in July 2026. A web-facing file manager with no security updates is a poor choice for new setups.

Sync is not backup
- Turn on versioning.
- So an accidental delete can be rolled back.
- Keep a separate backup.
- Sync spreads deletions and ransomware to every device.
- Keep one copy off-site.
- A single house is a single point of failure.
- Test a restore.
- An untested backup is a hope, not a backup.
Pair it with a photo library: our Immich guide covers the Google Photos side.