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An Open Source Defragmenter

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The term UltraDefrag is a shorthand for the Ultra Defragmenter and holds no connection with potential owners of registered trademarks or other rights. All trademarks, brands, and names are the property of their respective owners.

UltraDefrag is an open source disk defragmenter for Windows. It can quickly defragment everything including files which are usually locked by Windows. For instance, UltraDefrag can re-join paging and hibernation files.

Available Interfaces  |   Features  |   System Requirements  |   Translation


UltraDefrag 6.1.0 has been released

This release features completely rewritten documentation. A bit later it will be included in UltraDefrag v7 along with a bunch of bug fixes. If you believe some information is missing there, don't hesitate to drop us a note.

The Change Log contains the full list of changes.

Download the stable release.


Posted on 2015-04-19





  • Currently FAT, exFAT and NTFS are supported. (enhanced in 6.0.0)
  • Defragmentation of files and folders including system files and file system meta files. (enhanced in 5.1.0)
  • Full optimization of the drive, which processes all files despite of their fragmentation. (enhanced in 6.0.0)
  • Quick optimization of the drive, which mainly processes fragmented files. (enhanced in 6.0.0)
  • MFT optimization, which processes the MFT only. (enhanced in 5.0.1)
  • Filtering of files to process by name, fragment count and size and file size. (enhanced in 6.0.0)
  • Drive processing can be interrupted automatically after a defined amount of time.
  • User defined log file creation, which highly simplifies reporting bugs. (enhanced in 5.0.6)
  • Drives needed to be checked by CHKDSK are excluded. (enhanced in 5.0.5)
  •

Graphical User Interface:

  • Graphical display of the drives cluster map. (enhanced in 5.0.7)
  • Modern design with menus and tool bar. (enhanced in 5.0.3)
  • The current progress and all important information are displayed in the drives list. (enhanced in 5.1.0)
  • A final action can be specified to be executed after processing the drives. (new in 5.0.0)
  • Color coding of the usage of the cluster map. (enhanced in 5.0.7)
  • Localization can be done by the user or by one of the 63 included language packages. (enhanced in 5.1.0)
  • The window can be minimized to the system tray. (new in 6.0.0)
  • The progress can be displayed on the task bar icon under Windows 7® and above. (new in 6.0.0)
  •

Command Line Tool:

  • Useful for automation through scheduled tasks or batch scripts.
  • Integrated into Explorer's context menu. (enhanced in 6.0.2)
  • Specify options through command line arguments or environment variables. (enhanced in 5.0.0)
  • On demand, display of the graphical cluster map.
  •

Boot Time Interface:

  • Useful to process locked system files. (enhanced in 5.0.0)
  • An interactive mode is available too. (enhanced in 5.0.0)
  •


  • Available as plain text and HTML page. (enhanced in 5.0.3)
  • Includes all information about the fragmented files. (enhanced in 5.0.4)
  •


  • Two configurations are available, full and without GUI. (enhanced in 5.0.0)
  • All features can be configured through command line arguments. (new in 5.0.0)
  • Selections of previous installations are retained. (enhanced in 5.0.3)
  • Destination folder can be specified. (enhanced in 5.1.1)
  • Log file creation on failure of silent installation. (new in 5.1.0)
  •



Desktop PC: Windows NT 4.0, 2000, XP, Vista, 7, 8

Server: Windows NT 4.0, 2000, 2003, 2008, 2008 R2, 2012

32-bit, 64-bit and Itanium Editions



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