Syncthing synchronises folders directly between devices with no server in the middle. There is no account, no storage quota, and no third party holding the data, because the data never leaves the set of machines you nominate.
It is the right tool when the requirement is that files stay on your hardware, and the wrong tool when you want a web interface to browse them from anywhere.
Decisive facts
- Peer to peer sync with no central server
- TLS encrypted transfers between authenticated devices
- File versioning with several retention strategies
- Selective sync and per-folder ignore patterns
- Runs on desktop, server, and Android