Is it a Virus?
✔ NO - Safe
Must be in C:\Program Files\Syncthing\syncthing.exe or C:\Program Files (x86)\Syncthing\syncthing.exe
Warning
Daemon running in background
Syncthing typically runs as a background service/daemon and may start at login
Can I Disable?
✔ YES
You can disable or stop the Syncthing daemon when not syncing
What is syncthing.exe?
syncthing.exe is the Windows executable for the Syncthing decentralized file synchronization daemon. It runs in the background to keep folders in sync across devices without a central server, using peer-to-peer connections and encrypted transfers.
Syncthing runs as a single daemon that uses a peer-to-peer topology, exchanging encrypted data directly between devices via REST API calls and WebSocket updates. It watches configured folders and propagates changes incrementally.
Quick Fact: Syncthing emphasizes privacy by design, syncing data directly between devices without storing files on a central server.
Types of Syncthing Components
- Core Daemon: The syncthing.exe process runs the synchronization engine in the background.
- Web GUI: Local web interface served by the daemon for configuration and monitoring.
- API/CLI Access: Local REST API and CLI calls interact with the daemon for automation.
Is syncthing.exe Safe?
Yes, syncthing.exe is safe when it is the legitimate file from the Syncthing project downloaded from official sources (github.com/syncthing/syncthing or syncthing.net) and not modified.
Is syncthing.exe a Virus or Malware?
The real syncthing.exe is NOT a virus. Malware may imitate names; verify signatures and paths to be sure.
How to Tell if syncthing.exe is Legitimate or Malware
- File Location: Must be in
C:\Program Files\Syncthing\syncthing.exe or C:\Program Files (x86)\Syncthing\syncthing.exe. Any other location is suspicious.
- Digital Signature: Right-click syncthing.exe → Properties → Digital Signatures. Should show a valid signature from "The Syncthing Authors".
- Resource Usage: Normal usage is low when idle, higher during active syncing. Abnormally high usage when idle is suspicious.
- Behavior: Syncthing should run as a background daemon when configured; repeated launches without user action may indicate malware.
Red Flags: If syncthing.exe is located in unusual folders (like Temp, AppData\Roaming, or System32), runs at startup without user consent, lacks a digital signature, or shows unexpected network activity, scan with trusted antivirus. Look for similarly named files.
Why Is syncthing.exe Running on My PC?
syncthing.exe runs because the Syncthing daemon is active to monitor folders, communicate with peers, and serve the web GUI for local configuration.
Reasons it's running:
- Active Sync Operations: You have folders configured and syncing with one or more devices; the daemon runs to handle transfers.
- Background Services: Syncthing runs in the background to maintain up-to-date copies without constant user interaction.
- Automatic Startup: Syncthing is set to start automatically when Windows boots, keeping your folders in sync as soon as the system starts.
- Peer Discovery: Local network or DHT/relay discovery creates connections to peers for syncing data.
- Web GUI/API Access: The built-in web GUI is hosted locally (https://localhost:8384) and may be accessed by other tools, keeping the daemon busy.
Can I Disable or Remove syncthing.exe?
Yes, you can disable syncthing.exe. You can stop the daemon when not syncing and uninstall it if you no longer need it.
How to Stop syncthing.exe
- End Individual Tasks: Open Windows Task Manager, locate syncthing.exe, and End Task or End Process.
- Close Web GUI: Close any open syncthing web GUI tabs or browsers connected to localhost:8384.
- Prevent Startup: Task Manager → Startup tab → Disable Syncthing.
- Disable Background: In the Syncthing GUI, go to Settings → Local and disable startup options if present.
- Stop Services: If running as a Windows service, stop the service named Syncthing.
How to Uninstall Syncthing
- ✔ Windows Settings → Apps → Apps & Features → Syncthing → Uninstall
- ✔ Delete configuration folders: C:\Users\<YourUser>\AppData\Local\Syncthing and C:\Users\<YourUser>\AppData\Roaming\Syncthing
- ✔ Delete program folder: C:\Program Files\Syncthing or C:\Program Files (x86)\Syncthing if present
Common Problems: High CPU or Memory Usage
If syncthing.exe is consuming excessive resources during syncing or idle, try the following fixes.
Common Causes & Solutions
- Too Many Active Folders: Reduce the number of watched folders or adjust per-folder settings to limit syncing events.
- Large File Transfers: Pause or adjust bandwidth and transfer settings to throttle usage during peak times.
- Stalled Sync or Missing Devices: Ensure devices are online, share the correct device IDs, and re-approve peers in the GUI.
- Outdated Version: Update to the latest Syncthing release to fix bugs and improve performance.
- Resource-Intensive Extensions or Plugins: If addons are used through the API, review instrumentation and disable unnecessary features.
- Antivirus Interference: Temporarily whitelist syncthing.exe or adjust antivirus settings to avoid scanning in real time.
Quick Fixes:
1. Open Syncthing Web GUI at https://localhost:8384 to review active folders and devices
2. Pause heavy transfers and limit bandwidth in Settings
3. Restart syncthing.exe from Task Manager or Services
4. Update to the latest version from https://github.com/syncthing/syncthing
5. Whitelist syncthing.exe in your antivirus/firewall
Frequently Asked Questions
Is syncthing.exe a virus?
No, the legitimate syncthing.exe is part of the Syncthing project. Verify the file path (C:\Program Files\Syncthing\syncthing.exe or C:\Program Files (x86)\Syncthing\syncthing.exe) and signatures from The Syncthing Authors.
Why is syncthing.exe using so much CPU?
CPU usage spikes during large or many concurrent syncs, or when indexing new files. Check the Web GUI's activity, reduce watched folders, or pause heavy transfers.
Can I delete syncthing.exe?
You can uninstall Syncthing via Windows Settings if you no longer need it. Your synced data will remain in the configured folders only if you choose to remove them.
Can I disable syncthing.exe?
Yes. Stop the daemon, disable startup, and close the GUI. If you rely on Syncthing for syncing, consider leaving it disabled only temporarily.
Why does Syncthing start at Windows boot?
If configured to start automatically, Syncthing will launch at boot to keep folders synchronized. Disable it in Task Manager → Startup or in the GUI settings.
How do I reduce Syncthing's memory usage?
Limit the number of watched folders, avoid large file trees, and ensure you are on the latest stable release. Consider enabling per-folder quotas or a memory cap if available.