Total Commander - A Shareware file manager for Windows® 95/98/ME/NT/2000/XP/Vista/7, and Windows® 3.1.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
fman - An unexpected gift. January 07, 2018 by Michael. One of the nice things that happened last week was an fman user writing in to say that 1) fman "is THE BEST SOFTWARE" (sic). And that 2) he would like to send me a $50 tip.
TreeSize - TreeSize tells you where precious disk space has gone to.
Solid Explorer - Solid Explorer is a powerful Android file manager featuring access to most popular cloud storages, root access and easy extensibility.
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.