FreeFileSync

FreeFileSync is an open source folder comparison and synchronisation tool for Windows, macOS and Linux, used to mirror data to backup disks and NAS shares, keep two folders in step and run scheduled copy jobs. A FreeFileSync download is free for private individuals; businesses, organisations and government agencies are required by the developer’s terms to use the paid Business Edition, which matters for most readers of this site.

It compares folders first and shows you exactly what will be copied, updated or deleted before anything happens, then saves the setup as a batch job you can run from Task Scheduler, cron or its own RealTimeSync watcher.

FreeFileSync at a glance

What it does

• Compares folders by time and size, by content (binary) or by size only, and shows the differences in a two-pane grid.
• Synchronises in several modes: two-way with conflict detection, mirror, update, or custom rules per change type.
• Keeps a history of deleted and overwritten files through versioning, so a mirror does not silently destroy data.
• Copies locked files on Windows through the Volume Shadow Copy Service.
• Works with local and network folders, SFTP, FTP/FTPS, Google Drive and MTP devices.
• Handles long paths over 260 characters, symbolic links, NTFS permissions and extended attributes.
• Saves configurations as batch jobs with exit codes for scripting, and RealTimeSync runs them when a folder changes.
• The Donation and Business Editions add parallel file copy, e-mail notifications and an auto-updater; Business adds silent installation.

How sysadmins use it

Nightly mirror of a file share to a NAS with versioning

1. Add the source (left) and the target (right), using UNC paths such as \fs01data and \nas01mirrordata.
2. Click Compare with the default “File time and size” method.
3. Open the synchronisation settings, choose Mirror, and set deletion handling to Versioning with a folder like \nas01mirror_versions so removed or replaced files are kept.
4. Add exclusions in the filter, for example System Volume Information, $Recycle.Bin and *.tmp.
5. Save the setup as a batch job (.ffs_batch), enable auto-close and choose how errors are handled for unattended runs.

Schedule the job with Windows Task Scheduler

1. Create a task that runs daily with “Run whether user is logged on or not” and an account that can reach both shares.
2. Set the action to the FreeFileSync executable with the batch file as its argument.
3. Always use UNC paths in the job: mapped drive letters are not available to scheduled tasks and are a common cause of failed runs.

A wrapper script lets you alert on the exit code (0 success, 1 warnings, 2 errors, 3 cancelled):

"C:Program FilesFreeFileSyncFreeFileSync.exe" "D:JobsMirror-FS01.ffs_batch"
if not %errorlevel% == 0 (
  echo FreeFileSync finished with code %errorlevel%
  exit /b %errorlevel%
)

Sync on change with RealTimeSync

1. Open RealTimeSync and load your .ffs_batch file; it picks up the folders to watch and the command to run.
2. Set an idle time, so the job starts only after changes have stopped for that many seconds.
3. Save the setup as an .ffs_real file and start it at logon with "C:Program FilesFreeFileSyncRealTimeSync.exe" "D:JobsMirror-FS01.ffs_real"; with an .ffs_real argument it skips the dialog and starts monitoring.

Install and first run

• Windows: Windows 7 to 11, installer needs admin rights for a machine-wide install. Silent installation (/silent) is only available in the Business Edition.
• macOS: 10.12 or newer. Grant Full Disk Access in Privacy & Security if you sync protected folders.
• Linux: x86-64 builds for the major distributions; run jobs from cron by calling the FreeFileSync binary with the batch file path.
• Network targets: SFTP needs outbound TCP 22; FTP in passive mode needs the server’s passive range open.
• Portable use: the portable ZIP is part of the Donation Edition; the standard version is installed locally, which the developer recommends in general.

Limitations

• The free standard version is for private individuals only. Company, school and government use requires the Business Edition.
• It is a synchronisation tool, not a full backup product: no disk images, no deduplication, no restore catalogue. Versioning keeps old files, but you have to set its retention limits yourself.
• No Windows service mode; unattended runs rely on Task Scheduler, cron or RealTimeSync in a user session.
• A wrong direction in a mirror job deletes data on the target. Always check the preview on the first run.
• Linux builds are x86-64 only.

FreeFileSync vs alternatives

Syncthing replicates folders continuously between machines peer to peer, without a central share, and is free for any use; FreeFileSync is better for scheduled, previewed one-way jobs to a NAS or SFTP server. Robocopy is built into Windows and scriptable, but has no preview grid or versioning. For image-based backups of workstations, AOMEI Backupper Standard fills the gap, and Cobian Backup is an older Windows freeware backup scheduler that is no longer developed.

FAQ

Is FreeFileSync free?

Yes for private individuals: the standard version is free and open source. The developer’s terms say businesses and other organisations must use the paid Business Edition.

Is FreeFileSync open source and safe?

The source code is published under the GPL-3.0. It is actively maintained with frequent releases; install it from the official site to get genuine, current builds.

Is there a FreeFileSync portable version?

Yes, but the portable ZIP is part of the Donation Edition (and the Business Edition). The standard free version is installed normally.

Is there FreeFileSync for Mac and Linux?

Yes. It runs on macOS 10.12 or newer and on major 64-bit Linux distributions, with the same batch-job format as on Windows.

Mirror vs Update: what is the difference?

Mirror makes the right side an exact copy of the left, including deletions. Update only copies new and changed files to the right and never deletes there.

How do I schedule FreeFileSync?

Save the configuration as a batch job, then run FreeFileSync.exe with the .ffs_batch path from Windows Task Scheduler or cron. Use UNC paths for network shares.

FreeFileSync vs Syncthing: which should I use?

Use FreeFileSync for controlled, scheduled copies you want to preview; use Syncthing when several machines must stay in sync all the time without manual runs.

How do I exclude a folder in FreeFileSync?

Open the filter settings and add the folder to the Exclude list, for example Temp relative to the base folder or *node_modules for any level.

Last checked against official sources: 30 September 2026 (developer website: freefilesync.org). Versions and licence terms change — confirm on the developer's site before deploying in production.