Syncthing can sync a selected folder between a Linux computer and an Android phone once you pair the devices and share the folder. You can do it without a cable or a cloud-storage account. The setup uses Syncthing on Linux and Syncthing-Fork on Android.
What you need
- A Linux computer with Syncthing installed from its distribution’s package repository.
- An Android phone with Syncthing-Fork. The project repository identifies the current Android wrapper and points to its Releases or F-Droid builds.
- A folder you want to sync, plus a network connection for the devices to communicate.
Syncthing synchronizes folders you choose to share. Changes made on one device can appear on the other, so choose a folder whose contents you want kept in sync.
Install and start Syncthing on Linux
- Install the package for your distribution. For example, Debian-based systems can use
sudo apt install syncthing; Arch-based systems can usesudo pacman -S syncthing. - Start Syncthing and open its local interface. In a browser on the Linux computer, go to
http://127.0.0.1:8384. Set GUI credentials when prompted. - Enable startup at boot if you want the service to run automatically. On an Arch-style system, the demonstrated systemd command is
sudo systemctl enable --now syncthing@YOUR_USERNAME.service. ReplaceYOUR_USERNAMEwith your Linux account name.
systemd is the Linux service manager. The command above is for the Arch-style service shown in a Linux setup demonstration; package and service commands can vary by distribution.
Pair the Android app and Linux device
- Open Syncthing-Fork on Android and complete its setup prompts. The setup requires All Files Access and notifications, and recommends disabling battery optimization so Android does not stop the app in the background. All Files Access is broad: it can permit the app to read, modify, and delete files on the phone or connected storage. Grant it only with that scope in mind.
- Pair the devices in both directions. Show the Linux device’s QR code in the web interface, scan it with the Android app, then accept the device connection on both sides.
- Share the folder. Select the Linux folder in Syncthing and share it with the paired Android device. Accept the shared folder on the phone and choose its local folder location.
DistroTube’s English-language screencast demonstrates Linux installation, QR pairing, reciprocal device acceptance, folder sharing, a successful sync, and systemd startup.
Check that the folder syncs
Create a small test file inside the shared folder on Linux, then check that it appears in the corresponding Android folder. Make a simple change to the test file and confirm that the updated version arrives on the other device. This checks both the folder share and the device connection before you rely on the setup for other files.
Protect files and keep recoverable versions
On Linux, a system-wide Syncthing service can create new received files with permissions that let other local users read them, depending on its umask. A umask controls the default permissions given to new files. ArchWiki documents a systemd drop-in example using UMask=0077 to restrict access to newly created files. Existing files need their permissions handled separately.
File versioning can help recover an earlier copy after an overwrite or deletion. Linuxiac recommends Syncthing’s Simple File Versioning option with three retained versions. That is a guide recommendation, not a required default.
If Linux and Android do not find each other
Check whether the router uses access point isolation, whether both devices are on the same subnet, whether they can reach each other, and whether firewall rules or multicast restrictions block discovery. These checks help separate a network discovery problem from a folder-sharing or Android background setting.
In one Syncthing support case, the user reported that manually specifying device addresses resolved their connection problem. Treat that as a configuration-specific workaround, not a universal fix.
