DiskReport is described as 'diskreport.net allow to generate an online report of disk space usage. Periodic run allow reports of size and file count variation, usefull to find growing files or directory' and is an app in the OS & Utilities category. There are four alternatives to DiskReport for a variety of platforms, including BSD, Linux, Mac, Windows and PortableApps.com. The best alternative is TreeSize. It's not free, so if you're looking for a free alternative, you could try Baobab Disk Usage Analyzer or ncdu.
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).