WinDirStat: Windows Directory Statistics

WinDirStat (Windows Directory Statistics) is a disk usage statistics viewer and cleanup tool for Windows. On start up, WinDirStat reads the whole directory tree once and then presents it in three useful views:

- The directory list, which resembles the tree view of the Windows Explorer but is sorted by file/subtree size,
- The treemap, which shows the whole contents of the directory tree straight away,
- The extension list, which serves as a legend and shows statistics about the file types.

Visit the WinDirStat blog for more up-to-date information about the program.

Note: If you are looking for an alternative to WinDirStat for Linux, then you are looking for KDirStat (apt-get install kdirstat on Debian-derivatives), and the alternative to WinDirStat for MacOS X is Disk Inventory X or GrandPerspective.