Freeware Descriptions:
UltraDefrag is a powerful, open source defragmentation tool for Windows. It´s engine is very fast, because it is created as a kernel-mode driver.
Here is complete features (taken from authors site):
There are three interfaces to them: graphical, console and native. The first is very useful, because it uses cluster map visualization. Console is good for task scheduler, and native tool - for advanced users and programmers.
UltraDefrag´s design is very ergonomic: no skins, no localization, no animation and so on. It´s a truely small and powerful program! It can be used on Windows 2000, Windows XP, Windows Server 2003 and Windows Vista. NT 4.0 support is currently unavailable.
Features:
- very fast defragmentation, because engine is kernel mode driver and has optimal algorithm.
- very small engine written in pure C language.
- nice graphical interface - compact and comfortable.
- safety, because file moving is realized with special system calls.
- simple to use.
- generate html reports.
- has useful filters.
- free: distributed with full source code under the GNU General Public License.
What’s New in version 2.1.1:
- Most of the known bugs were fixed.
- Japanese translation was added.

File Size / OS:
- 332 KB / Windows 9x - ME - 2000 - NT - XP - 2003 - Vista
Download UltraDefrag 2.1.1: