Syncthing Server Setup - Free Real-Time Sync

Understand the Model First

One honest correction before anything is installed: Syncthing has no server and no cloud at all. It is a free, open-source program that runs on each of your devices and syncs folders directly between them, encrypted, peer to peer. The "server" in this setup is simply one device — usually a desktop PC, a mini PC or a small home server — that stays switched on all the time and holds a copy of everything, so your laptop and phone always have a partner to sync with.

Three ideas explain everything Syncthing does. Every device is equal — there is no master PC, and if two devices are online they exchange whatever the other is missing. Device IDs are the security — each install generates a unique Device ID, and two devices sync only after both sides have accepted each other's ID; there is no password to guess. And folders have types — on each device a folder is Send & Receive, Send Only, or Receive Only.

Transfers are encrypted end to end with TLS. On the same network the devices talk directly — fast, and nothing touches the internet. If the hub PC is switched off, nothing breaks and nothing is lost: the other devices can still sync with each other directly, and everything catches up automatically when the hub comes back on.

Install Syncthing on the Hub PC

Pick the hub honestly: it should be a machine that stays on — an office desktop, a mini PC, an old laptop, or a small Linux server. A laptop that travels with you is a poor hub, because every other device then waits for it to come home.

Download Syncthing only from syncthing.net or your Linux distribution's official repository — it is a popular tool and fake download sites exist. On Windows, run the installer and let Syncthing start with Windows. On Linux, install the syncthing package. You can also start Syncthing manually from a terminal:

syncthing

Open the Web Console and Set a Password

Syncthing is managed from a web interface. With Syncthing running, open this address in your browser on the hub PC:

http://localhost:8384

Then open Settings and set a GUI username and password. The interface is only reachable from the machine itself by default — keep it that way.

Make Syncthing Start Automatically on Linux

On a Linux hub, enable Syncthing as a system service so it starts at boot and survives reboots, instead of only running while you are logged in:

sudo systemctl enable --now syncthing@yourusername

Replace yourusername with your own Linux username — the service runs as that user, so it syncs that user's folders. On Windows this step is already covered by letting Syncthing start with Windows in Step 2.

Pair Your Other Devices

Install Syncthing on the laptop and phone as well, then pair each one with the hub. On the new device, open its interface and copy its Device ID (Actions → Show ID) — the Android app shows a QR code for the same ID. On the hub, choose Add Remote Device, paste or scan the ID, give the device a clear name, and save. On the new device, accept the hub when the request appears.

Both sides must accept — that double handshake is the security model working, not a bug. A device only ever syncs with devices it has explicitly paired.

Share Your First Folder

Now give the devices something to sync. On the hub, choose Add Folder, set a short label and pick the folder path — for example this one on Windows:

D:\OfficeFiles

Or this one on Linux:

/home/anshu/OfficeFiles

Open the folder's Sharing tab and tick the laptop and phone. On each device, accept the folder and choose where it should live there — the paths do not need to match, only the folder's internal ID matters. Watch the first sync complete and the folder state change to Up to Date on every device.

Turn On Versioning — Sync Is Not a Backup

Two finishing touches turn a demo into a setup you can rely on. First, file versioning on the hub: open each folder's Versioning tab on the hub and choose Staggered or at least Trash Can. Plain sync copies deletions to every device instantly — versioning is what keeps yesterday's copy of a file you deleted or overwrote by mistake.

Second, phone photos, send only: on the phone, share the camera folder as Send Only and receive it on the hub as Receive Only. Photos land on your PC automatically, deleting them on the phone never deletes the PC copy, and nothing ever flows back to fill the phone.