MyDefrag (formely called JKDefrag) is a free application that is designed to help us to defragment our hard disks and optimize the free space in Flash, SSD disks, USB devices, pen drives, etc. While installing, we can choose to install any or all of the following components: script interpreter, standard scripts, example scripts, user's manual, and screensaver. We can also set this program to perform automatic optimizations every so often. It is possible to use this program to analyze only, defragment only, consolidate the free space in hard disks, SSD disks, Flash disks, and so on. There are three defragmentation and optimization modes that can be set to run periodically: daily, weekly, and monthly. They correspond to a light defragmentation, a medium defragmentation, and a high defragmentation, respectively. This program is easy to operate by anyone. There is a disadvantage, and that is, the program takes a huge amount of time to perform even the lightest defragmentation, and it freezes more times than desired. MyDefrag runs under the following operating systems: Windows 7, 2008, VIsta, XP, and 2003.