UltraDefrag is a powerful disk defragmentation tool for Windows. It is the first open source defragmenter with full support of system locked files defragmentation. Actually all files including registry hives and paging file can be processed by UltraDefrag during the Windows boot process.

Also one of the primary goals of the UltraDefrag design is doing the job as fast as possible.

UltraDefrag has the following features:
Driver:
- Currently FAT, exFAT and NTFS are supported.
- Defragmentation of files and folders including system files and file system meta files.
- Full optimization of the drive, which processes all files despite of their fragmentation.
- Quick optimization of the drive, which mainly processes fragmented files.
- MFT optimization, which processes the MFT only.
- Filtering of files to process by name, fragment count and size.
- Drive processing can be interrupted automatically after a defined amount of time.
- User defined log file creation, which highly simplifies reporting bugs.
- Drives needed to be checked by CHKDSK are excluded.

Graphical User Interface:
- Graphical display of the drives cluster map.
- Modern design with menus and tool bar.
- The hight of the drives list can be adjusted.
- The current progress and all important information are displayed in the drives list.
- A final action can be specified to be executed after processing the drives.
- Color coding of the usage of the cluster map.
- Localization can be done by the user or by one of the 58 included language packages.

Command Line Tool:
- Useful for automation through scheduled tasks or batch scripts.
- Integrated into Explorer's context menu.
- Specify options through command line arguments or environment variables.
- On demand, display of the graphical cluster map.

Boot Time Interface:
- Useful to process locked system files.
- An interactive mode is available too.
Reports:
- Available as plain text and HTML page.
- Includes all information about the fragmented files.

Installer:
- Two configurations are available, full and without GUI.
- All features can be configured through command line arguments.
- Selections of previous installations are retained.

Supported filesystems

The following filesystems can be defragmented by UltraDefrag: FAT12/16/32, NTFS; UDF (on Vista and later systems).

There are few system restrictions which applies to the disk defragmentation. Unfortunately UltraDefrag cannot walk away these restrictions:

* Directories on FAT volumes cannot be moved. This is a well known FAT driver mistake, it cannot be fixed.
* $MFT, $Bitmap and other internal NTFS files cannot be defragmented on Windows versions prior to Windows 7. Because NTFS system driver prevents accessing them.
* NTFS volumes with cluster size greater than 4 kilobytes cannot be defragmented on Windows 2000.
* UltraDefrag cannot defragment volumes containing more than 4.294.967.295 clusters.

Never try to run UltraDefrag on NTFS v1.2 formatted volumes under Windows NT 4.0, because this may crash your system. NTFS 1.2 had a beta status and an appropriate system driver was not reliable.