Best Free Disk De-fragmenter

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When testing defragmenter software, we evaluate it with these parameters:

  • Speed of analysis on fragmented files: Isn't it speed we want from our computer?
  • Speed of defrag;
  • Some extras: such as scheduled defrag, shutdown PC when done, etc.;
  • Defrag capabilities: Why is this placed in last position? Because almost all of today’s defragmenters can perform this task with very similar results.

With these parameters in mind, we found a few we could recommend with the best of these as good as any commercial product.

Read also Fragmentation: Why does it happen? and Defragmentation: Do you need it? at the end of this page.


Rated Products


A simple and super fast defragmenter

Our Rating: 
License: Free (Open source)
System files defragmentation. Incredibly fast in all tasks. Power (scripting) features.
Some settings only accessible by configuration file (txt).
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Unbelievable power user options for everyone without having to configure any script

Our Rating: 
License: Free
For average and power users.
Not regularly updated.
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Perform quick defragmentation with decent file reorganization

Our Rating: 
License: Free (Private/Educational use)
Very solid piece of software. Updated regularly. Now with S.M.A.R.T. monitoring.
No optimization feature yet.
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My Defragmenter  

A simple and intuitive defragmenter plus a full scheduler

Our Rating: 
License: Free
Well recognized Ultradefrag engine. Excellent scheduler.
Not regularly updated.
Read full review...

Also reviewed but not included:

  • Puran Defragmenter
  • O&O defrag free edition
  • Others

Feel free to suggest any software not already mentioned for review.


Related Products and Links

You might want to check out these articles too:


Fragmentation: Why does it happen?

Suppose you are browsing the web, downloading your favorite songs and installing an application all at the same time, how does your system write all these files without any interruption to your activity? Well it's simple: it responds to all applications' write requests (I/O operations) by writing all files at a continuous location on your disk.

Representation of a disk track:

(Fig. 1)

Yellow: Temporary written internet files
Red: Installation (Game)
Blue: Song cache

The purpose of disk defragmenters is to reorganize such files which are supposed to be together. An ideal situation after defragmentation would look like this:

(Fig. 2)

But what happens when you uninstall, delete, or simply clean your temporary files? Imagine yourself uninstalling the application (game) you installed. The disk could look like this:

(Fig. 3)

The white zone is empty space without fragmentation. A disk looking like this will have just a little or even imperceptible impact on performance. In this case defragmentation is needed but not critical.

The last thing you want to see is a hybrid combination. Files very fragmented fig 1 and empty disk space fig3 but instead of contiguous clean sectors you'll find what we call fragmented empty space. And this is what it looks like:

(Fig. 4)

This is the worst case scenario. Overall system performance will be compromised and fragmentation is critical. You should defragment (defrag) or let your defragmenter schedule and execute the defrag process for you.


Defragmentation: Do you need it?

Standard mechanical HDDs (hard disk drives) will benefit from defragmentation and continuous disk use, because when spinning, it keeps remagnetizing the HDD plates. But if you own an SSD (solid state drive) you SHOULD NOT defrag or install any defragmenter application because it will shorten the life of the drive.



This software review is copy-edited by Ian Richards. Please help edit and improve this article by clicking here.

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Average: 4 (239 votes)


Definitely down as of now: Could just be server maintenance, or as you suggest something more severe. Time will tell. MC - Site Manager.

It came back on 10th April. Problem was with faulty dns-server, none could access the site although it was up and running.

Thank you! That means I don't have to hunt down another product with fewer features to fill a gap.
Thanks for the update. :) MC

Watch out. UltraDefrag just blew in the middle of an Optimization on one of my PCs running Win7. It's got plenty of power and space on the HD. My system is hosed for now.

Were you using a Beta version? Can you isolate the issue to a particular setting or specific action. I am only asking because the product has consistently been highly ranked, and after testing on my personal machines, the licensing permits use within government and business environments. I have substituted UltraDefrag on many Windows 7 machines within my workplace due to the faster defragmentation times as well as the optimmization. I have it on about 30 desktops now in place of Defraggler. It has been performing very well on the Dell Optiplex Systems I am using it on. Thanks for your feedback. A word of caution to all: The open source and free tools are offered as is. The Open Source products generally have an active group of followers that are ready, willing, and able to assist with any issues and bugs. In many cases, I find the forums for these products to have better support than paid software. You may want to pose your specific situation in a forum. SourceForge can probably link you to the community. Keep me posted.

Nope, I was using the newest stable version. I started the full slower optimization and left the house. Came back later to a shutdown PC. Started it up and got the message that Windows couldn't start. Two options... repair or start Windows normally. Starting Windows normally would just put me in the same spot. When I tried a repair, Windows gave me a message that it couldn't do it. Can't remember exactly what the message was. Luckily, I keep most of my stuff on an external drive! I would love to have been able to look at the events if Windows was able to log them. I still have the drive if you know where I could look for the events.

I also like the many options that this software gives you but I'm scared! Going back to Defraggler for now.

That is definitely unfortunate. The technician in me would love to look at the Event logs and the dump file. I am the editor of the defragmentation page on a voluntary basis as a way to contribute some of my experience and to answer questions related to this topic. Consequently, I have to be cautious about what I write and how I write it. I do not advocate that anyone opens or browses through Windows system files without the explicit warning that doing so can trash the Operating System. However, I can tell you that the log files are located within the Windows system files. More specifically, the .evt files are located within the %SystemRoot%\System32\Config folder. The files can be imported into a Comma Separated Values format (.csv)that is very similar to Excel. If you decide to have an IT Pro retrieve them for you, the answer to the crash will probably be in both the Application and System logs. As to Defraggler, it has always been stable, frequently updated, and on my personal top three list of de-fragmentation tools. I have installed Defraggler and it's sister program CCleaner on more machines than I can count. Defraggler will do a great job for you, is highly customizable, can be set to replace the Windows De-Fragmentation tool, and run automatically through a scheduled task. You can't go wrong with all of that. In my testing, if I find a negative impact on Windows from any of the products, I will certainly share that as part of creating an objective and unbiased list. Thanks again for sharing the information with me and the other readers!

Why not to review and include Ultimate Defrag Freeware Public Domain Edition?

It's old, released 2008, and non-supported version of the main commercial one, but still rather good and advanced defragger alternative, and in my opinion should be mentioned here. Is it for the same reason that the O&O freeware is not reviewed? Both are more adware than freeware :)

"More than just a defragger, UltimateDefrag is also a hard drive file placement optimizer that enables you to defrag and place your files in the areas on your hard drive where you achieve maximum performance. 80% of the time you only use 20% of the files on your hard drive. UltimateDefrag places your rarely used files out of the way and onto the slower performing areas of your hard drive making your drive perform like a new, almost-empty drive. Version 1.72 includes unspecified updates."

Read more: UltimateDefrag Freeware Edition - CNET

Moderators comment: Be sure to only use the "Direct Download Link" button to avoid the cnet wrapped installer and it's unwanted components.

It is definitely something I can look at. I am hesitent to download installations from CNET because of the instalation wrappers that attempt to redirect home pages and add superfluous toolbars, etc. I will look for an alternate download site. Thanks for sharing your thoughts. Do you have an idea of why it has not been updated more recently than 2008? Two of the products I am testing have already been updated within the last month. Active updates indicate that a product is heavily used and the developers have an interest in meeting the needs of the customer base. Thanks again for sharing!
I have just recently joined as an editor of this topic and Ultimate Defraf-Freeware-Edition is on a list of products to test. Many free products are as supported. It costs money, either through donations, ads, or other avenues of revenue to support the availability of freeware products. I do want to emphasize the moderator's comment that with CNET Downloads, the software is bundled inside a wrapper. If you choose the default installation or don't take care to uncheck and decline additional offers, you will ens up with more than the software. I appreciate your conviction for UltimateDefrag. Thank you!

I don't use it myself, I prefer other one, but it is in my opinion a good disk defragmenter to be mentioned and reviewed on a freeware disk defragmenter list as an alternative to these that are already mentioned.

Yeah the CNET is crap nowadays. Hard to find a download link for it and that was the first one. It seems that Disktrix isn't offering it anymore, although they seem to still host it.

Here is a better alternative link:

And Direct Download link from Disktrix:
[Edited out, direct download link is not allowed.]

I appreciate the suggestion. I will definitely check it out. To all of you, I will run my comments through a spell and grammar check before I post again. Thanks for overlooking the handful of typos! I'm a networking guy by trade, and writing anything other than Standard Operating Procedures, Network maps, and sub-netting is new to me. I did get my career start on the desktop and software end of IT though. I got into trying, using personally, and implementing in a business environment, good open source and freeware programs that help to keep computers running optimally. Disk De-fragmentation is one of those areas that can create a genuinely visible improvement in the speed and performance of a computer. Thank you again!

Hello rmitch,

hope you have a good time with this.

One thing about defragging I've rarely seen mentioned is that many programs perform badly if hiberfile.sys and pagefile.sys get in the way. Temporarily disabling these, even on a disc with lots of room on it, can magically allow the program to do its job. I'm not sure if I'd advise the inexperienced to do this though.

One bonus with temporarily disabling the pagefile is that it gets defragged properly, something that a lot of programs don't actually seem to manage.

Thank you! One of the criteria I am considering is the native ability of a product to scan these files that Windows locks when the Operating System is running. Many of the alternatives include an option now to scan and defrag the paging file and hiberfile.sys. For those unfamiliar with the concept, the pagefile.sys is a portion of the hard disk that Windows uses as a supplement to RAM (memory). Windows will use the system RAM for the high priority tasks and services running and the paging area for inactive or queued functions until it needs them and they are moved to RAM. In Unix and Linux, the equivalent is the swap file. Feel free to Google this. I try hard to explain concepts in plain English, but some of the specifics become lost in translation. Thanks for the very valid, and very excellent reference to the hiberfile.sys and pagefile.sys.