And tkdu, which is abandoned, but still works great. You can pipe the output of du into it, which is useful if you want to visualize a remote server.

https://github.com/daniel-beck/tkdu

And the great thing about ncdu is that you won't have to traverse the filesystem again and again as you narrow down where the disk is going, if you don't already have a good guess.

xdu as well

https://karl-voit.at/2014/03/25/xdu/