How to Set Up Syncthing on a Chromebook

Syncthing runs on a Chromebook through the Linux development environment, also called Crostini. Install it from the official Debian repository, start its user service, share a ChromeOS folder with Linux, then pair the Chromebook with another Syncthing device. Linux support must be available on your device; a work or school administrator may disable it. Syncthing syncs changes, including deletions, so keep a separate backup of important files.

1. Turn on Linux support

Open Settings > About ChromeOS > Developers. Next to Linux development environment, select Set up and complete the prompts. ChromeOS creates a Debian container and opens Terminal. In Terminal, select the penguin tab if prompted, then refresh package lists:

sudo apt update

2. Install Syncthing from its official repository

The Debian package may lag behind Syncthing’s current stable release. The Syncthing project maintains a signed APT repository. Add its release key and the stable v2 source, then install:

sudo apt install -y curl ca-certificates
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -L -o /etc/apt/keyrings/syncthing-archive-keyring.gpg https://syncthing.net/release-key.gpg
echo "deb [signed-by=/etc/apt/keyrings/syncthing-archive-keyring.gpg] https://apt.syncthing.net/ syncthing stable-v2" | sudo tee /etc/apt/sources.list.d/syncthing.list
sudo apt update
sudo apt install syncthing

Confirm the package installation when APT prompts you. These steps follow the official Syncthing APT instructions.

3. Start Syncthing and open the dashboard

Enable the per-user service so Syncthing runs in the background for your Linux session:

systemctl --user enable --now syncthing.service

In Chrome, open http://localhost:8384. ChromeOS tunnels localhost connections into Crostini. Syncthing’s GUI listens on localhost by default; keep that setting for Chromebook use and do not expose port 8384 to your network. If the service unit is unavailable, run syncthing --no-browser in Terminal and leave it open while syncing. Use one start method at a time. See the official autostart guide.

4. Share a Chromebook folder with Linux

In ChromeOS Files, choose a folder such as My files > Downloads > Sync. Right-click it and select Share with Linux. Linux can then access it under /mnt/chromeos; the example path is usually /mnt/chromeos/MyFiles/Downloads/Sync. Sharing gives Linux access to that folder without moving it. See the ChromeOS Linux setup guide.

5. Add the folder in Syncthing

In the dashboard, select Add Folder. Set a label such as Downloads Sync and use the folder picker to choose the shared path. Leave the folder type at Send & Receive for two-way syncing, then save. If the folder is missing, check Files to confirm Linux sharing is enabled and verify the path under /mnt/chromeos.

6. Pair another device and share the folder

Start Syncthing on the other computer or phone. In its interface, choose Actions > Show ID and copy the device ID. On the Chromebook, select Add Remote Device, paste the ID, give it a recognizable name, and save. IDs are intended to be shared with peers.

Pairing is mutual: accept the Chromebook on the other device, and add its ID there if prompted. On the Chromebook, edit the folder and select the remote device in its sharing options. Save. The Syncthing getting started guide covers the device and folder exchange.

7. Accept the folder and confirm syncing

On the other device, accept the folder offer and choose its local destination. Back up existing files before connecting folders with important contents; matching names do not ensure that the data is identical. When both devices are online, the dashboard should show the peer connected and the folder status reach Up to Date. Create a small test file and confirm that it appears on the other device.

Changes and deletions sync across devices. For recovery options, enable file versioning on a receiving device and keep an independent backup. See Syncthing’s file versioning documentation.

Troubleshooting

• Dashboard does not open: Check systemctl --user status syncthing.service and reload http://localhost:8384. ChromeOS localhost forwarding or an administrator policy can affect access.
• Peer is disconnected: Confirm both devices are running Syncthing and have accepted each other’s IDs. Direct sync uses TCP and UDP port 22000; local discovery uses UDP 21027. Firewalls may block these. Relays can help when a direct connection fails, though transfers may be slower. Read the official firewall guide.
• Direct inbound sync is needed: ChromeOS port forwarding can expose Linux ports to other devices. Forward the sync ports only if needed, and keep the web GUI on port 8384 private. If you bind that GUI to 0.0.0.0, Syncthing recommends a strong password and HTTPS.

For Linux availability and setup details, see Google’s Chromebook Linux instructions.