Syncthing Setup Guide for Private File Sync

Last updated: March 15, 2026

Syncthing is an open-source, decentralized file sync tool that transfers data directly between your devices using peer-to-peer connections, eliminating any cloud server and keeping your files under your complete control. Install Syncthing on macOS via Homebrew, Windows via installer, or Linux via package manager, then add devices by scanning QR codes or pasting device IDs and selecting folders to sync. This guide covers installation on all platforms, device pairing, folder configuration, security settings including TLS encryption and device verification, and practical setup for privacy-conscious file management across multiple devices.

Prerequisites

Before you begin, make sure you have the following ready:

A computer running macOS, Linux, or Windows
Terminal or command-line access
Administrator or sudo privileges (for system-level changes)
A stable internet connection for downloading tools

Step 1 - Install Syncthing

Syncthing runs on Windows, macOS, Linux, and several other platforms. The installation methods vary depending on your operating system.

macOS Installation

On macOS, you can install Syncthing using Homebrew:

brew install syncthing

After installation, launch Syncthing in the background:

syncthing serve &

Linux Installation

Most Linux distributions package Syncthing in their repositories. On Debian or Ubuntu:

sudo apt install syncthing

For the latest version, download the binary directly from the GitHub releases:

wget https://github.com/syncthing/syncthing/releases/download/v1.27.2/syncthing-linux-amd64-v1.27.2.tar.gz
tar -xzf syncthing-linux-amd64-v1.27.2.tar.gz
./syncthing-linux-amd64-v1.27.2/syncthing

Windows Installation

Download the Windows installer from the official website or use the portable version. The portable version works well for power users who prefer not to install software system-wide.

Verify your installation by accessing the web UI at http://localhost:8384 after starting Syncthing.

Step 2 - Initial Configuration

When you first run Syncthing, it generates a unique device ID and configuration files in your home directory. On Linux and macOS, these are stored in ~/.config/syncthing/.

Understanding the Web Interface

The web interface provides access to all Syncthing settings. Key sections include:

Folders: Manage which directories are synchronized
Devices: Add other devices to your sync network
Settings: Configure global preferences including network, UI, and advanced options

Adding Your First Folder

To synchronize a folder between devices:

Click “Add Folder” in the web interface
Enter a folder label (e.g., “Documents” or “Code Projects”)
Specify the folder path on your local system
Configure sharing options by selecting which devices can access this folder

The folder path must exist on your system before Syncthing can sync it. Create the directory first if needed:

mkdir -p ~/Sync/Documents

Step 3 - Connecting Devices

Syncthing identifies devices by their unique Device ID, a long string of characters generated during first startup. To connect two devices:

Finding Your Device ID

Access the web interface and click the “Actions” menu (gear icon), then select “Show ID”. Your Device ID will display along with a QR code for easy mobile device setup.

Adding a Remote Device

On each device, navigate to “Add Device” and enter the other device’s ID. Give the device a friendly name for easier identification. After adding the device, you can choose which folders to share with it.

Network Configuration

Syncthing uses TCP port 22000 for local connections and can traverse NAT via UPnP or relaying through the Syncthing discovery servers. For better privacy, you may want to disable relay connections and discovery servers:

Go to Settings → Connections
Uncheck “Enable Relay Service”
Uncheck “Global Discovery” and “Local Discovery” if you prefer manual IP entry

For manual connections, specify the address directly:

tcp://192.168.1.100:22000

Security Best Practices

Syncthing encrypts all transfers using TLS, but additional security measures strengthen your setup.

Enabling HTTPS for Local Access

By default, Syncthing’s web interface uses HTTP. Enable HTTPS for local access:

syncthing -gui-address=https://127.0.0.1:8384

Configuring a GUI Password

Protect the web interface with authentication:

Navigate to Settings → GUI
Enable “GUI Authentication”
Set an username and password

For enhanced security, use environment variables to store credentials rather than storing them in configuration files:

SYNCTHING_GUI_USER=admin SYNCTHING_GUI_PASSWORD=your_secure_password syncthing

Firewall Configuration

Ensure your firewall allows Syncthing’s communication port:

UFW example
sudo ufw allow 22000/tcp

Advanced Configuration

For developers and power users, Syncthing offers advanced features through configuration files.

Using the Config File

Edit ~/.config/syncthing/config.xml directly for precise control. After editing, trigger a configuration reload:

syncthing -reload

Ignoring Files

Create a .stignore file in each folder root to exclude files from synchronization:

Ignore temporary files
*.tmp
*.swp
*~

Ignore version control
.git/
.svn/

Ignore OS files
.DS_Store
Thumbs.db

Selective Synchronization

For large folders, use folder markers to synchronize only specific subdirectories. Create a .stfolders file listing the paths you want to sync:

Projects/webapp
Projects/mobile
Documents/Important

Step 4 - Automate Syncthing Startup

Systemd Service (Linux)

Create a systemd service for automatic startup:

[Unit]
Description=Syncthing - Open Source Continuous File Synchronization
After=network.target

[Service]
Type=simple
User=yourusername
ExecStart=/usr/bin/syncthing serve -no-browser -gui-address=http://127.0.0.1:8384
Restart=on-failure

[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl enable syncthing
sudo systemctl start syncthing

LaunchAgent (macOS)

For macOS, create a LaunchAgent plist in ~/Library/LaunchAgents/:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.github.xor-gate.syncthing</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/local/bin/syncthing</string>
        <string>-no-browser</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

Load the agent:

launchctl load ~/Library/LaunchAgents/com.github.xor-gate.syncthing.plist

Troubleshooting Common Issues

If devices won’t connect, verify both have the correct Device ID added and that firewalls allow port 22000. At least one folder must be shared between them. If files aren’t syncing, check the .stignore file for patterns that block them, then review the Syncthing log for specific error messages. High CPU usage can be reduced by lowering the concurrent file operation limit in Settings → Advanced → Max Concurrent Items.

Frequently Asked Questions

How long does it take to guide for private file sync?

For a straightforward setup, expect 30 minutes to 2 hours depending on your familiarity with the tools involved. Complex configurations with custom requirements may take longer. Having your credentials and environment ready before starting saves significant time.

What are the most common mistakes to avoid?

The most frequent issues are skipping prerequisite steps, using outdated package versions, and not reading error messages carefully. Follow the steps in order, verify each one works before moving on, and check the official documentation if something behaves unexpectedly.

Do I need prior experience to follow this guide?

Basic familiarity with the relevant tools and command line is helpful but not strictly required. Each step is explained with context. If you get stuck, the official documentation for each tool covers fundamentals that may fill in knowledge gaps.

Is this approach secure enough for production?

The patterns shown here follow standard practices, but production deployments need additional hardening. Add rate limiting, input validation, proper secret management, and monitoring before going live. Consider a security review if your application handles sensitive user data.

Where can I get help if I run into issues?

Start with the official documentation for each tool mentioned. Stack Overflow and GitHub Issues are good next steps for specific error messages. Community forums and Discord servers for the relevant tools often have active members who can help with setup problems.