Syncthing

Syncthing uses a peer-to-peer protocol to transfer data directly between your devices, so no file ever passes through or is stored on a central cloud server. There is no subscription, no storage limit beyond your own hardware, and no company with access to your files. This makes it ideal for privacy-conscious users who want cloud-like sync without the cloud.

Syncthing runs on Windows, macOS, Linux, Android, and other platforms, keeping devices in continuous real-time sync. It features conflict resolution, selective sync, and per-folder ignoring rules. The Android app makes it easy to include a phone or tablet in your sync mesh.

When direct connections fail, for example when both devices are behind NAT, an optional relay infrastructure helps establish the connection. Communication is always encrypted end-to-end using TLS, so the relay cannot read your data. This keeps the network secure even when devices cannot reach each other directly.