UltraDefrag is powerful, smart and reliable OpenSource defragmentation tool for Windows. It's engine is very fast, because it is created as kernel-mode driver. They are three interfaces to them: graphical, console and native. First is very useful, because it use cluster map visualization. Console is good for task scheduler, and native tool - for advanced users and programmers. Design of the UltraDefrag is very ergonomic: no skins, no localization, no animation and so on. It's true small and powerful program!