Syncthing
Peer to peer folder sync between your own devices, no server needed
Syncthing keeps folders in sync directly between your devices, encrypted in transit, with no central server and no account. It is MPL-2.0 and does one job very reliably.
Best for when
- you want the same folder on several devices without a cloud account
- you want your phone's photos copied to a home server automatically
- you want something that runs for years with little attention
Watch out for
- deletions and corruption sync too, so it is not a backup
- devices must be online at the same time, so an always on node helps
- conflict files appear when two devices edit the same file and need cleaning by hand
Sync without a cloud in the middle
Each device runs Syncthing, you pair them once, and chosen folders stay identical across them. There is no server holding your files, so there is nothing to rent and nothing to leak in the middle.
It shines for working folders: notes, project files, a phone's camera folder sent to the home server. Versioning options keep old copies of changed files for a while, which saves you from some mistakes.
What to understand first
Sync is not backup. A file deleted or corrupted on one device is deleted or corrupted everywhere, a few seconds later. Pair it with real backups, or at least enable file versioning on the receiving side.
It is light on resources, but large folders take time and CPU on the first scan, and devices must be online at the same time to sync, unless one of them, like a home server, is always on.
