TreeSize is a powerful file and disk space manager and it is built in Delphi. According to the developer’s site “The software analyses all stored data across your systems and visualizes the results in meaningful charts and statistics. Find out where your disk space has gone at a glance and take immediate action if necessary. For this purpose, TreeSize provides you with a wide range of file management options.” Additionally, they say “The world-renowned solution is optimized for handling large file volumes and complements Windows Explorer. A high degree of automation is enabled by command line parameters and management of scans scheduling directly in a comfortable, graphical user interface.” And it has existed since 1997 (so over 20 years!). This is a powerful solution that works great for finding where all your hard drive space went (especially on servers).