Linux users are spoiled for choice when it comes to backups and file syncing. Rsync has been around forever, cron jobs are just a config file away, and most desktops ship with some sort of backup app baked in. But once your needs go beyond "copy this folder once a week," things get complicated fast.

That's where FreeFileSync and Syncthing come in. They solve related problems, but in very different ways, and that's exactly why it makes sense to use both.

FreeFileSync is your heavy-duty backup and synchronization workhorse. It's perfect for scheduled backup jobs, mirroring drives, or when you need fine-grained control over exactly how files get synced.

Syncthing, on the other hand, is all about keeping files synchronized across multiple devices in real time. It's decentralized, encrypted, and quietly works in the background. It's perfect for keeping your documents, photos, or project files available on your laptop and workstation.

Let's dig into both.

Backup Command Center

FreeFileSync is one of those apps that looks intimidating at first glance, but once you understand its logic, it quickly becomes indispensable. The interface is packed with options, but everything's laid out sensibly once you know where to look.

First things first, head over to the FreeFileSync website [1] and download the installer tarball. Once you've got it, extract and run it with

$ tar zxvf FreeFileSync_*.tar.gz
$ ./FreeFileSync_*.run

The installer will ask you a few questions. By default, it installs to /opt/FreeFileSync and makes the application available to all users on your system. If you're the only user or prefer a different location, you can change these settings during installation. Once it's done, the app will anchor itself in the Applications menu.

When you first launch FreeFileSync, you're greeted with what looks like a busy control panel. Don't let it overwhelm you. The layout is actually pretty logical. The two main panels show the two locations that you want to work with (Figure 1). These could be local folders, external drives, or even remote locations. Use the Browse button at the top of each panel to navigate to any folder in your filesystem.

Figure 1: Always select Compare before syncing in FreeFileSync to catch unintended deletions or overwrites.

In addition to the local folders, FreeFileSync also works with remote locations. Clicking the cloud icon next to the Browse button opens a new window that helps you configure remote access (Figure 2). FreeFileSync can connect to remote folders via FTP or SFTP. Just select the one that you want to use and enter the connection details, including the server address, username, and password or SSH key. There's also support for Google Drive. For this, you'll need to authenticate through your browser the first time, but after that your Google Drive appears just as another folder available for syncing.

Figure 2: FreeFileSync can sync with remote servers and Google Drive directly, without needing third-party mount tools or FUSE filesystems.

Sync Methods

The most important decision in FreeFileSync is choosing a synchronization variant. This determines how changes flow between folders. Use the arrow key next to the green gear icon to select the sync mechanism:

• Two-Way, the default option, treats both the left and the right folders as equals. Files added, modified, or deleted in either location are reflected in the other, making it useful for keeping two working directories identical. However, it can be dangerous if you're not paying attention: If you delete a file on one side, it will also disappear on the other side.
• Mirror is the classic backup behavior, where the left folder is treated as the source. FreeFileSync copies all new and updated files to the right and deletes anything on the right that no longer exists on the left. The source folder is left untouched.
• Update is a safer, additive backup option. New and changed files from the left are copied to the right, but nothing is ever deleted on the backup side.

The Mirror option works best as a set-and-forget backup where you want your backup drive to be an exact replica of your computer. The Update option works best for archival backups. For instance, it's ideal for backing up photos and videos from your smartphone. You can then delete them from your phone to save space, without worrying they'll be zapped from the backup drive on subsequent runs.

One of FreeFileSync's smarter features is how it handles deletions and overwrites. For local drives, you can just enable the Recycle bin option in the synchronization settings (the green gear icon).

For more advanced control, you can enable the Versioning option, which allows you to keep multiple versions of old files by moving them into a timestamped folder. You can also set a retention period for FreeFileSync to automatically clean up old versions and save space (Figure 3).

Figure 3: Enabling file versioning in FreeFileSync creates a safety net, allowing you to restore files if they are accidentally overwritten or deleted during a sync.

Once everything is configured, you can save the entire setup as a batch job by heading to File | Save as batch job. To run the backup job, you can double-click on the batch file or set up a cron job to have it run on a schedule.

Real-Time Sync Without the Middleman

Syncthing takes a completely different approach to file synchronization. Instead of scheduled backups or manual syncs, it maintains continuous synchronization between devices. Change a file on your desktop, and, within seconds, it's updated on your laptop – no cloud service, no central server, just peer-to-peer encrypted connections between your devices.

You can download the tarball for Linux from Syncthing's website [2] and extract it with

$ tar zxvf syncthing-*
$ cd syncthing-*
$ ./syncthing

Instead of using a traditional graphical user interface (GUI) app, Syncthing runs as a service and provides a web-based administration interface.

The first time you run it, Syncthing will generate some configuration files and encryption keys (stored under ~/.local/state/syncthing). Then, Syncthing will automatically open your default browser to http://localhost:8384, which is your Syncthing control panel. You will come back here whenever you need to configure anything (Figure 4).

Figure 4: Syncthing's web interface runs locally by default, keeping management access private unless you explicitly expose it.

By default, the interface is only accessible from the same machine, which is sensible. If you want to manage it from another machine, go to Actions | Settings and switch to the GUI tab. In the GUI listen address text box, change the address to 0.0.0.0:8384. While you're here, it's also a good idea to define a username and password to lock access.