ncdu is described as 'A disk usage analyzer with an ncurses interface, aimed to be run on a remote server where you don't have an entire graphical setup, but have to do with a simple SSH connection. ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like' and is a very popular disk usage analyzer in the os & utilities category. There are more than 25 alternatives to ncdu for a variety of platforms, including Windows, Linux, Mac, BSD and Flathub apps. The best ncdu alternative is WinDirStat, which is both free and Open Source. Other great apps like ncdu are WizTree, Baobab Disk Usage Analyzer, TreeSize and SquirrelDisk.
This program is unbelievably fast!