Tidy Up - Tidy Up is the duplicate finder and disk tidiness utility for expert users.

WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.

WinExt Free - Powerful Win utilities: fix registry issues, clean system junk, protect privacy, optimize system, find duplicates, show larger resources, see more info of recently accessed resources, monitor activity, make batch operations, synchronize resources.

WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.

CleanAfterMe - CleanAfterMe allows you to easily clean files and Registry entries that are automatically created by the Windows operating system during your regular computer work.

SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.