Diskzy

macOS tells you "System Data: 106 GB" and nothing else. Diskzy opens it up. It maps your whole disk, breaks System Data into named parts (caches, developer data, swap, backups, AI models and more), and marks each one safe to clear, look first, or managed by macOS. Clean up comes with a reason for every choice, and apps you have open are left alone. Uninstall removes an app together with everything it scattered around your Mac. Everything goes to the Trash, so nothing is gone until you empty it. Native Swift, about 3 MB, no analytics in the app, signed and notarized by Apple. Free for 72 hours, then $9 once for 2 Macs. No subscription.