ShowMan is described as 'Program to help recover disk space. Gives pie-chart view of disk usage, including unused space, with the ability to drill down into folders. Shows actual or nominal space occupied. Knows about the effects of cluster sizes' and is a Disk Usage Analyzer in the System & Hardware category. There are more than 50 alternatives to ShowMan, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux, BSD and Android. The best alternative is WinDirStat, which is both free and Open Source. Other great sites and apps similar to ShowMan are WizTree (Free Personal), TreeSize (Freemium), Baobab Disk Usage Analyzer (Free, Open Source) and DiskUsage (Free, Open Source).
WizTree scans your entire hard drive and shows you which files and folders are using the most disk space. It does this VERY QUICKLY. In fact, we believe WizTree to be the fastest application of this type currently available!
TreeSize Professional tells you where precious disk space has gone to. It can be started from the context menu of a local folder or a local drive and displays the size of each folder, including its subfolders.
Baobab Disk Usage Analyzer is a graphical application to analyse disk usage in any Gnome environment. Disk Usage Analyzer can easily scan device volumes or a specific user-requested directory branch (local or remote).
DiskUsage provides a way to find out which files and directories on the SD card of your Android phone are consuming the most space. It displays diagram with directories/subdirectories proportional to their size. Users are allowed to zoom in to look at specific directory content.
With DaisyDisk you can free up disk space by quickly finding and deleting big, useless files. The program scans any mounted disk and displays it on the sunburst map, where segments mean files and folders, proportionally to their sizes. The map is easy to read and navigate.
GrandPerspective is a small utility application for Mac that graphically shows the disk usage within a file system. It can help you to manage your disk, as you can easily spot which files and folders take up the most space.