Free (released under the GNU General Public License) disk defragment and optimize utility for Windows 2000/2003/XP/Vista/X64. Completely automatic and very easy to use, fast, low overhead, with two optimization strategies, and can handle floppies and USB disks/sticks. Included are a Windows version, a commandline version (for scheduling by the task scheduler or for use from administrator scripts), a screensaver version, a DLL library (for use from programming languages), and versions for Windows X64.

64 Bit version also available.

JKDefrag GUI adds an interface to JKDefrag.