This Open-Source File Backup App Is So Good I Can’t Believe It’s Free

The importance of backing up your files seems obvious, but choosing how gets complicated fast. The built-in Windows backup option is painfully basic, while decent software costs serious money. FreeFileSync claims to solve both problems and does so brilliantly.

Meet FreeFileSync

FreeFileSync is an open-source file synchronization tool that creates exact copies of your folders wherever you need them. Unlike dedicated backup apps such as Duplicati, which store files in compressed archives that require the app to restore, FreeFileSync keeps your files accessible in their original format.

FreeFileSync offers four sync modes:

• Mirror: Creates an exact copy of your source folder
• Two-way: Syncs changes in both directions
• Update: Copies only new or modified files
• Custom: Lets you define exactly how each type of file operation is handled, for greater flexibility

FreeFileSync also handles advanced backup setups with ease. It supports syncing to multiple destinations at once, making it perfect for following the 3-2-1 backup rule—three copies of your data, on two different types of media, with one stored offsite. You can chain multiple sync pairs in a single session, allowing you to back up to a local drive and a network location in one go.

Tools like Duplicati and Macrium Reflect are excellent for full-system backups of your Windows 11 PC. But if you need a fast, no-fuss way to copy key files and folders, FreeFileSync is a much simpler solution.

While the core software is completely free, FreeFileSync also offers a Donation Edition that unlocks extra features, such as faster performance through parallel file operations. For most people, the free version is more than enough, since it includes all essential functions. The donation-only features mainly benefit those who regularly sync giant datasets or work over slow network connections.

How to Use FreeFileSync to Automate File Backups

FreeFileSync isn’t the most intuitive backup tool and requires some technical know-how to get it working. While it’s powerful and flexible, you may find the interface overwhelming and the setup process confusing without referring to the documentation or community forums.

That said, once you get the hang of it, creating a basic backup is straightforward. Let’s walk through a simple example: mirroring up a folder from your primary storage drive to a secondary drive.

In FreeFileSync, click the + icon to select your source folder on the left—this is what you want to back up. Choose your destination on the right—whether that’s an external drive, network location, or cloud sync folder.

Before syncing, check the comparison settings by clicking the gear icon next to Compare (F6). I use the default File time and size option, which is fine in almost all cases. Only switch to File content if you need absolute accuracy and can afford the extra time, as it’s much slower on large folders. Skip File size unless you know what you’re doing.

If you’re backing up photos or videos, turn on Ignore time shift [hours] in the comparison settings. This helps FreeFileSync avoid re-copying files because of small time differences (like when daylight saving time changes or when you’re copying between Windows and a NAS).

Next, configure your sync settings. Click the green Gear icon by the Synchronize tab and select Mirror mode. This creates an exact copy of your source folder and removes files from the backup that no longer exist in the original.

While Mirror mode is useful for keeping your backup clean and preventing old files from piling up, its behavior also means it will copy corrupted files, those locked by ransomware, and similar. And if you delete a file, its "backup" will be deleted as well. To combat this, you’ll need to set up file versioning, as explained below.

Another option is to choose Update mode, which only adds files to your backup folder and will never delete them.

Two-way sync mode has its uses, too, but is more niche. For example, it could be useful to place copies of files into cloud storage, where someone else also works on them.

Setting up Filters (F7) can save both space and time during backups. Click the funnel icon to open the filter settings. Here, you can exclude folders or files that don’t need to be backed up—like temporary files or folders that can be recreated later.

Before running any sync, always click Compare first to preview exactly what changes FreeFileSync will make before anything is copied or deleted.

Enable Versioning to Keep Backup Copies of Changed Files

To protect important files from accidental changes or deletions, enable versioning in FreeFileSync. This feature keeps older versions of files so you can recover them if something goes wrong during sync.

Click the Gear icon next to Synchronization (F8) in the main window to open the sync settings. Select the Versioning option under Delete and overwrite. Then, click Browse and choose a location for the versioning folder, such as E:\Backups\Versions.

Finally, pick a naming style; timestamps are a reliable overall choice. This way, FreeFileSync keeps backup copies of previous versions just in case you accidentally overwrite something important.

Automating and Scheduling Backups

FreeFileSync doesn’t include built-in scheduling, so to automate backups, you’ll need to create a batch file and schedule it using Windows Task Scheduler. While it’s not the most user-friendly process, at least you can set it up once and forget.

After setting up your sync pairs and verifying everything with Compare, click File > Save as Batch Job. This saves your sync configuration as a .ffs_batch file. In the batch job window, you can customize several options—such as whether the sync runs silently in the background, whether errors are shown, and whether a log file is created.

Make sure to check the boxes for Run minimized and Auto-close if you want the task to run without your input. Once saved, this batch file becomes a self-contained script that you can run manually or schedule via Task Scheduler to run automatically.

Save each backup job as a batch file—one for documents (runs daily), another for video projects (runs after each editing session), and a weekly full backup of everything else.

Alternatively, you can use RealTimeSync, part of FreeFileSync, to monitor folders and trigger backups when files change. Unlike Task Scheduler, RealTimeSync detects and copies files in real-time depending on the set interval, so it’s ideal if you want to back up changes as soon as they happen.

While the lack of native scheduling is a limitation, both Task Scheduler and RealTimeSync offer reliable workarounds once set up correctly. Just remember to test your scheduled tasks—there’s nothing worse than discovering your automated backups haven’t run for months.

FreeFileSync also offers a portable version that runs directly from a USB drive, allowing you to set up backups on multiple computers. It’s a convenient, plug-and-play option for quick, hassle-free use.

The Not-So-Good Bits of FreeFileSync

FreeFileSync’s interface feels like it’s stuck in 2010. While it gets the job done, the cluttered layout and technical jargon can overwhelm newcomers. Even simple tasks like setting up filters or understanding sync directions often require digging through documentation or watching tutorials.

Cloud support is another area where FreeFileSync falls short. It natively works with Google Drive and supports FTP and SFTP connections for server-based storage. But if you’re using Dropbox, OneDrive, or other cloud services, the situation is trickier.

You’ll need workarounds, like installing the desktop apps to sync with local folders or using third-party tools such as Mountain Duck to mount cloud storage as drives in File Explorer. For a tool that’s actively maintained in 2025, this setup feels way outdated.

Download: FreeFileSync (Free, premium version availbale)

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Despite these quirks, FreeFileSync gets the basics right. It’s reliable, completely free without ads, and gives you total control over your backup strategy. While it focuses on file and folder backup rather than full system imaging, it’s perfect for keeping your documents, photos, and personal data safe.