What are some alternatives?
When comparing KDirStat and WizTree, you can also consider the following products
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
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.
TreeSize - TreeSize tells you where precious disk space has gone to.
Cygwin - Cygwin is a set of tools that provide Linux and POSIX functionality to Windows.
Baobab - Distributor of workload automation, financial statement reporting, data access, IT Asset Management and Service Desk software solutions.
Process Hacker - Process Hacker is a feature-packed tool for manipulating processes and services on your computer.