Best Free Folder Synchronization Utility

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Introduction

File synchronization utilities help you keep updated copies of files or folders in two or more locations, such as different computers, network drives, USB drives, or online storage. While a file sync utility could be used as a simple backup tool (called one-way syncing), its real power lies in keeping an identical set of working files in two or more locations. An example of this would be keeping current versions of the same data files on both your home computer and office computer (two-way syncing). File sync utilities keep track of which files you create or change, or even delete in one location, and can create, change, and delete those same files in the other location.

Criteria for the Evaluating a Synchronization Utility: A good synchronization utility would have most or all the following features.

Should support two-way synchronization of files.
Should be able to replicate any source folder even if the files are in use.
Should detect conflicts or file collisions. These occur when a file has changed in both locations since the last sync operation. This requires that a database or journal be kept by the utility.
Should propagate deletions and detect file renames. This also requires a log file of previous operations.
Should support filters and rules for fine tuning what files are, or are not included in the sync operations.
Should show a preview of what is going to take place during a sync operation, and allow the user to easily over-ride any actions desired.
Should have a job scheduler and the ability to automatically detect and launch sync operations when a destination becomes active. (Such as plugging in a USB drive)
Should support syncing to both local and network locations.

There are are a lot of contenders in this category, but based on the criteria above, three stand out.

Discussion

[2]

Pure Sync is the top pick in this category. The only major feature that I found it lacks is the ability to copy open or locked files in the free edition. It has a fairly good set of filters and rules to fine tune what files are included in the job operations. It creates a database during the initial sync operation which it uses to detect file collisions or conflicts, and propagate deletions thereafter. It has a good preview of what files are going to be copied, updated, or deleted when performing a sync job. It has a nice scheduler and supports enabling auto sync for storage such as USB drives. It also has some special options for copying photos from digital cameras. Be aware that while it supports syncing to network locations, syncing with FTP is only supported in the paid version. Over all I was very pleased with its numerous features and ease of use, and heartily recommend it to the average user.

[3]

FreeFileSync is another solid contender here. In fact I had a hard time choosing between FreeFileSync and PureSync for my top pick. The thing I like the best with this utility is its very clear and informative interface. The preview is very easy to understand, and file collisions and deletions are more readily recognizable than in PureSync. If you require a sync program that can copy files that are in use or locked, FreeFileSync has you covered there too! Unfortunately it only has very basic filters, no auto sync feature, and no direct support for FTP. My final complaint would be that its help file is a little sparse. Those few flaws aside, I found it to be well designed and easy to use.

[4]

Allway Sync is my third recommendation. It is a very well rounded product with loads of features. It has a very robust filter and rule set and definitely has the edge here over the other two previously reviewed products. It also offers support for FTP, scheduling, and auto syncing. It has a very thorough help file which can be of great benefit especially to those who are new to synchronization programs. One draw back I found is that while it does detect file collisions and deletions, it is not very clear how to choose which versions of conflicting files to keep and which to overwrite. You should also be aware that in the free version of Allway Sync there is a file opreration limit of 40,000 files in any 30 day period. So if you have a large amount of files to synchronize on a daily basis you might need to look at a different choice. Also note that it does not support copying locked files as the developers feel it could compromise data integrity.

Honourable Mentions.

SyncBack: [5] Supports file compression, and can verify file integrity after job completion.
Synkron: [6] Had a lot of votes for this one in the comments section.
File Synchronizer [7]: Is good if you are looking for a minimalistic or simplistic utility.

Best Free Folder Synchronization Utility

PureSync [10]

FreeFileSync [13]

Allway Sync [14]