SpaceMonger

I use DaisyDisk for my Macs and WizTree for Windows

Spacemonger is probably the oldest piece of non-updated software I still use. I've been using it continuously for over 20 years, about the same length as I've been using Winamp 2, and just recently used it to clear out some large files to create a full-disk backup.

It still works blazing fast on hard drives that are 1000 times the size than the drives that existed when it was programmed, and nearly as well as 20+ years ago (there are some occasional crashes when removing some system protected files, but easy to just open it up and scan again). I never made the jump to Spacemonger 2 because in the early years that I started using it, I was in high school without a credit card.

I emailed the author in December 2020 to see if there was a way to enable HiDPI on it, since that's the only real flaw of it right now. He responded 3 months later with a very personal message that I really appreciated.

qdirstat - https://github.com/shundhammer/qdirstat

I'm a bit confused at why people are saying it isn't updated, as its now a paid Stardock product (officially licensed, according to Sean Werkema's resume):

https://www.stardock.com/products/spacemonger/

The Stardock version 3.0 Build 1711 is from 2018, so that is a while since the last update and there's still no HiDPI. There's also a bug where it interprets 0-byte placeholder files as 8GB giants. But 2018 seems to be a newer update than what people here are suggesting.

But v3 isn't free, and I've not tried the old freeware / open source version, so I don't know if newer actually means "better".

They have stopped developing it long time ago. Current alternative is SpaceSniffer http://www.uderzo.it/main_products/space_sniffer/