UltraDefrag is a free, easy-to use-utility that defragments files and optimizes their placement on your hard drive. It sports both a simple but effective Windows graphic interface and a command line alternative. You can also schedule it to defrag or optimize during the Windows boot sequence. It's available in versions for 32-bit and 64-bit Windows.
Using UltraDefrag is simple, at least via the Windows interface. Simply select the drive you want to analyze, defragment, or optimize and press the appropriate button. The Analyze feature will show you a graphic sector table describing where files reside on the hard drive and report how fragmented they are. Defragment concatenates all parts of a file so that they are in contiguous sectors. Optimize on the other hand, is both mysterious and automatic. I could find nothing in the documentation that tells you exactly which files are being moved or why.
Normally, optimization means moving large, frequently accessed files to the outer, faster parts of the hard drive and smaller, less frequently accessed files inwards--with all as far out towards the rim as possible. From what I gleaned with questions to the developers, UltraDefrag is simply moving files as far out as possible with no delineation by file or other criteria. It would be nice if you could specify files (in my case my Outlook PST file) à la UltimateDefrag 1.72 Public Domain Edition.
UltraDefrag did a very nice job optimizing the hard drive--as far as consolidating free space. However, the program is not smart enough to leave SSDs alone. While SSDs will tell you that everything is organized in sectors, this is just what the drives tell the BIOS and operating system. In truth, data is stored and accessed far differently than a hard drive and can't be optimized by normal methods. Defragging also uses up an SSD's limited number of writes per cell at a faster rate. For more about defragging SSDs, see "Defragging: How, Why, and Whether."
As long as you avoid telling UltraDefrag to defrag or optimize your SSDs, you should do fine. It's a nice addition to any hard drive toolbox.