Many good alternative listed already. But I have quite liked FileLight which is cross platform https://apps.kde.org/filelight/ Likely not as fast as WizTree though. - Source: Hacker News / 26 days ago

You’ll need to boot into Desktop Mode to drill deeper regarding what’s installed on your SD card or internal storage. In Desktop Mode, you can navigate around using the built-in file explorer, Dolphin. You can also download and install Filelight from the Discover app store, if you want more of a visual aid while sifting through your files and directories. Source: about 1 year ago

I would open the Discover store in Desktop mode and download Filelight, which will help visualize the used space on your drive. It might help illuminate what’s taking up so much space, pun intended. Source: about 1 year ago

Use KDE Filelight, it's actively maintained unlike SpaceMonger. Source: over 1 year ago

Run this before assuming that it's some random program https://apps.kde.org/filelight/. Source: over 1 year ago

There are also more user-friendly and interactive tools to do this. I use and like ncdu, but there are others, such as duc. Source: about 1 year ago

I have used ncdu for a long time, and it's good if you have time to wait for it to get sizes, if you can't, Duc AKA "Dude, where are my bytes" has caching and is ready to apt install on Debian and Ubuntu repos https://duc.zevv.nl and it has different GUI options. It's slightly more complex but for larger volumes I use it instead of ncdu. - Source: Hacker News / over 1 year ago

I've used duc on Linux for a while. Can recommend. https://duc.zevv.nl/. - Source: Hacker News / almost 2 years ago

As a side note, once in a while I return to https://duc.zevv.nl/ as it is quite capable of visualizing where data is hiding alas only without access times to possibly identify stale data. Source: about 2 years ago

Is this the duc you're referring to? Source: over 2 years ago