The app
How it decides what is safe
Every one of the 44 categories carries a rating for what cleaning it costs you — and that rating, not a button, decides what can be cleaned in bulk and what cannot.
The four levels
- Safe to remove. Regenerates on its own. Cleaning confirms, then deletes.
- Review. Regenerates, but costs you a rebuild, a re-download or an app restart. Derived Data lives here.
- Move to Backup. Your data. There is no bulk clean at all: the button opens the list and you pick items one at a time, or move them to another drive.
- Protected. Cannot be deleted from here — your Photos library, macOS temp data. The row tells you what to do instead.
The point of the rating is that it is not advice. It is wired to what the interface will let you do, so a red flag cannot be cleaned in bulk however hard you click.
What it will not do
- Delete anything without a confirmation, ever. There is no one-click clean-everything.
- Touch a category whose app is open. Deleting a build tree during a build breaks the build, so a scheduled clean skips it and says so.
- Empty the Trash on a timer. The Trash is the undo for everything the app moves there.
- Count the same bytes twice. A folder another category already claims is left out of the broader one, so the totals add up.
- Remove the last copy of anything. In both duplicate finders one copy of each file is kept and is never even listed, so cleaning everything on screen cannot take the last one.
Measured, not estimated
Every figure comes from your own Mac. The disk gauge is your disk; the memory reading is your kernel's own statistics — on the machine this was built on, 18.09 GB held in 4.83 GB. Where a measurement cannot be made honestly the app says so rather than filling the gap: that is why there is no RAM purge button and no malware scan, and why each is replaced by the number it would have acted on.
A worked example: pictures saved twice
The picture finder was first built on Apple's own image-similarity model. Measured against a thousand real pictures it called two different bills, two pages of one report and two frames of one contact sheet the same picture — so it was rebuilt to compare pixels instead, and now claims only that it finds the same picture saved again. It misses a crop, and says so, rather than guessing and offering your photographs.