WinDirStat
Open Source
WinDirStat is a disk usage statistics viewer and cleanup tool for Windows based systems.
TreeSize
Freemium
TreeSize Free is a free disk space manager for Windows. The software shows you the sizes of folders including all subfolders.
Scanner
Free
Scanner is a tool uses a sunburst chart to display the usage of your hard disk or other media.
WizTree
Free
WizTree gives you more control over how you see your files, in addition to letting you learn more about them from one look.
SequoiaView
Free
SequoiaView is a disk browsing tool based on the principle of treemaps.
SpaceSniffer
Free
SpaceSniffer is a freeWare and portable tool application that lets you understand how folders and files are structured on disks.
JDiskReport
Free
JDiskReport enables you to understand how much space the files and directories consume on your disk drives, and it helps you find obsolete files and folders.
SpaceMonger
Commercial
SpaceMonger is a tool for keeping track of the free space on your computer.
MindGems Folder Size
Free
Folder Size is a freeware disk size analysis tool that will display the directory sizes and folder tree sizes.
Compare ncdu with alternatives
Compare MindGems Folder Size and ncdu and decide which is most suitable for you.