3.8 out of 5 with 25 ratings

FreeFileSync Reviews

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Good news: version 10.0, released on April 27 2018, no longer includes ads in the installer.
Previous versions used to bundle optional software that was checked by default.


Great program ruined by malware in the installer.

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I really loved this program but the malware introduced in the installer has caused me to abandon it. The last time I installed this program (on my fiancee's laptop) the installer got to the page asking to install some kind of adware. While reading through this page, after only a few seconds, the installer jumped to the next page and started installing Freefilesync (and, as I would eventually find out, the adware program I was trying to read about). My hands were not touching her laptop so I know I didn't accidentally hit a key. Just to be certain I uninstalled the program and ran the installer again. For the second time, I watched as the installer jumped to the next page after only displaying the option to opt-out the adware for a very brief few seconds. I, honestly, was not given enough time to reject the install of this adware (yontoo).

I intended to run a scan using Malwarebytes immediately after this but was in a hurry and had to leave to do something. I forgot about this issue and, within the next day, pop-ups and notifications for various obviously fake issues started displaying on her computer. I immediately ran a scan with Malwarebytes and cleaned up the mess that the adware/malware had made.

It is really sad to have to write off such a great program due to such a poor decision by the developers to support their work with malware.

[Edited by ecsa0014, January 29]


I strongly agree. The OpenCandy is a crap. I'll abandon it too.

Fortunately, OpenCandy has now been removed from the installer. There's still an option for installing optional (and needless) software, but that option can be switched off and the program is acceptable for use again.

It now copies a PMofStX.dll to a temporary folder in AppData\Local\Temp that is flagged by several AV programs as a Trojan in 9.8 and 9.9. And 9.9 my AV Web Reputation service complained of a call to a domain.

FreeFileSync: VSS, portable and triangle-sync

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Very important Advantages of FreeFileSync (FFS):

  • Triangle-sync as only Allway Sync, GoodSync, SyncLess or FreeFileSync can do.
  • VSS-support (Volume Shadow Service), only with VSS-Support it is possible to sync open files
  • Portable app with no need of admin rights.
    SyncLess, Synkron or Toucan are also portable, but have no VSS-Support.
  • No limitation of the number of synced files as with the free version of Allway Sync

Not very important Disadvantages of FreeFileSync (FFS):

  • FreeFilesync cannot synchronize WebDAV-files as only Allway Sync or GoodSync can do
  • FreeFilesync cannot synchronize "Windows Mobile" files or folders as only Allway Sync or GoodSync can do

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Very powerful, super easy to use and versatile. For those not used to command-line interfaces. Two ways, mirror, update and custom sync. Capable of syncing several folders at a time. I've never tested, but it is supposed to be able to sync from/to online storage via SFTP or FTP


No auto-deleting of synced files in both directions

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My personal impression: structured very clearly, and very impressing and simple user interface. But if You want to delete files on the other directory equal in what direction automatically, You cannot use it for synchronisation.
For this purpose there would be necessary a synchronisation data file in the synchronised directory, which FreeFileSync does not have and not need, because the deletion direction must specified from case to case. FreeFileSync is good for making identical copies of directories (Like backups in ONE direction)
Deletion automatically in both directions is possible with Synkron (Open Source), PureSync (Free for private use), totally perfekt with Allway Sync (but max. 20000 Files/month free, the only Sync Tool, able to sync Windows Mobile SD-Card or NAND-Memory and WebDAV and FTP-Online Memory direct adressable).


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  • Most Popular Open Source with Portableapps Support and has Backup, Incremental, Cloud, Scheduled Backup
  • but has Bad UI

By Far the Best Sync Tool

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This app is awesome. First it's free as in speech, second it's graphically intuitive and easy to use, and finally it's very flexible.

It made short work of the hopeless jumble of photo directory complete with overlapping backups, partially organized folders and so on.

So, yes it's midly annoying to have to pay attention during the install (I unintentionally installed some other app and then uninstalled it), but I'll take that over licenses, crippleware and so on. I'm sure that all of the people complaining donate to Open Source developers, right?

Either way the tool should be graded on it's own merits, maybe with an asterisk for annoying marketing. Otherwise you're doing a disservice to people like me who need a sync tool that works.


Easy to use, but no data integrity checks on copy operations

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I loved this when I first used it because it's very simple and easy. Plus, it's available in the PortableApps suite, which makes everything convenient. I already had FastCopy, which does data integrity verifications to make sure there are no copy errors, but I didn't know FastCopy could also do synchronization. The only downside to FastCopy is if you want to check the file comparison results, it doesn't have basic file comparison features like sorting etc. But, I trust FastCopy so much that I normally don't bother to double check the comparison results, so FastCopy does it all for me now.

When I REALLY want to play around with file comparison, there are many available tools that can do it, and FreeFileSync is one of the best of them. My favorite thing about it is how easy it is to use. Although it won't do a data integrity check after a copy operation, it will do checksums on the entire group of files, but that can take hours if you have lots of data. If you only have a small amount of data that only takes a few minutes, then that's probably good enough. Just do another file compare after you run the sync, and FreeFileSync will tell you if there's an error, so you can try copying the files again. It's not ideal, but it does work.

For data intergrity checks, my favorite tools are Corz Checksum, and MultiPar. Corz Checksum is by far the fastest tool I have ever seen - it's so fast, it's ridiculous. I've had cases that took 20 minutes that Corz Checksum could do in seconds. I use Corz Checksum to quickly check for problems in my data, and if any are found, I can fix it with MultiPar. MultiPar can do what Corz Checksum can do, but it's not as fast, so I usually don't use it until after Corz Checksum detects an error.

The most important reason to use both Corz Checksum and MultiPar is because of bugs. I found a bug in Corz Checksum once, that MultiPar found for me. Bugs happen! You can never be too cautious, or use too many data integrity and backup strategies.


Great tool

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Easy to use and clear settings/options.
If you want to sync files in Windows 8's Program Files directories, you should open this tool with administrator privileges.


Nod32 reported 'potentially unwanted application'

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nstB355.tmp\FreeFileSync-InstallManager.exe multiple threats cleaned by deleting - quarantined Event occurred on a new file created by the application: FreeFileSync_5.9_setup.exe.
nstB355.tmp\FreeFileSync-InstallManager.exe » NSIS » Script.nsi Win32/InstallMonetizer.AE potentially unwanted application
nstB355.tmp\FreeFileSync-InstallManager.exe » NSIS » vnktctrlr.exe Win32/InstallMonetizer.AD potentially unwanted application
nstB355.tmp\FreeFileSync-InstallManager.exe » NSIS » vnktctrlr.exe » NSIS » Script.nsi Win32/InstallMonetizer.AD potentially unwanted application
nstB355.tmp\FreeFileSync-InstallManager.exe » NSIS » license_YahooTB.rtf archive damaged - the file could not be extracted.


Far better than other sync tools for my needs.

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I was looking for something to backup new and updated games from my Steam library (over 200GB) to an external drive so I can uninstall games to free up space and not have to waste bandwidth re-downloading if I want to play them again.

With FreeFileSync, the scan/comparison results are presented well with lots of statistics, there are buttons to filter the results view with a single click, and I can exclude folders in the right-click context menu (sub-folders are not expanded automatically). The interface is kept simple by having certain elements context-based - buttons that don't have any use to your current task/step in the sync process are hidden. I accomplished what I was trying to do quickly and didn't need to refer to the help file.

The previous sync tools I had negative experiences with were DirSync Pro (too complicated) and Microsoft SyncToy (not complicated enough to be useful).


Backup tool - Excellent

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This has replaced my data backup software (Acronis) with the feature "file-versioning". This allows you to keep a current full backup whilst archiving any changes/deletions. This feature can't be emphasised enough and is more useful than most backup software that starts with a full version then keeps incremental or differential archive formats. It can run as a batch file and used VSS. No good for OS imaging or disaster recovery of OS.


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Great, simple, multi-optional program! I'm surprised I didn't leave a comment here much earlier. In addition, the program improves with each update, and does not deteriorate, as is now practiced by certain programs. The program helps a lot to save all important data. THANK YOU VERY MUCH!


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FreeFileSync is a good synchronizing program not as good as GoodSync but it is just fine, free and open source. Contrary to what old post mention I couldn't find any malicious software. After installation of any new software in my computers I always run Malwarebytes, Adwcleaner and RogueKiller. All three reported free of malicious codes.