Hidden Bar - A ultra-light MacOS utility that helps hide menu bar icons.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
Bartender Mac App - Bartender is an award-winning app for macOS that superpowers your menu bar, giving you total control over your menu bar items, what's displayed, and when, with menu bar items only showing when you need them.
WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.
Vanilla - Vanilla is a free Mac app that lets you hide icons from your menu bar.
SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.