Tidy MacOn this MacBook Air, CleanMyMac’s clean-up freed about 3 GB. Tidy Mac then split “System Data” into named parts and freed about 40 GB, all of it sent to the Trash first. The difference: most of the space wasn’t ordinary junk, it was inside System Data.
The Mac
A developer friend of the maker (MacBook Air). His MacBook Air kept saying the disk was almost full. He was paying for CleanMyMac, and its clean-up freed about 3 GB.
What CleanMyMac did
CleanMyMac ran its clean-up and freed about 3 GB. That’s typical when most of the space isn’t caches or junk: the cleaner clears what it is built to clear, and the rest stays where it is.
What Tidy Mac found
Tidy Mac split the mystery “System Data” into named parts. On a developer’s Mac that is mostly build files, simulator and device-support files, package caches and old installers. Tidy Mac ticked only the items marked Safe to clear and moved them to the Trash first. About 40 GB came back. Now he keeps an eye on it from the menu bar, where Tidy Mac charts his free space day by day.
Before and after
| CleanMyMac | Tidy Mac | |
|---|---|---|
| Space freed on this Mac | about 3 GB | about 40 GB |
| Price | $39.95 a year (1 Mac) | $9.99 once (2 Macs) |
CleanMyMac price: annual plan for one Mac, as listed in 2026.
Why the gap is so big
macOS files many unrelated things under one grey bar called System Data: local Time Machine snapshots, iPhone and iPad backups, developer files from Xcode and Docker, downloaded AI models, and old installers. Each can be tens of gigabytes. A cleaner that only looks for caches and logs will never touch them, so the number it frees is small even when the disk is full.
Tidy Mac measures each of those places, names it, and sorts what it finds into Safe to clear, Worth a look or Kept, so the big items are visible instead of hidden in one bar.
Check your own Mac
- Buy Tidy Mac, download it with your key and open it. Home splits System Data into named parts.
- Open Clean and look at System junk and Project folders, biggest first.
- Keep the items marked Safe to clear ticked; look at anything marked Worth a look before you tick it.
- Click Clean. Everything goes to the Trash, and History can put it back.
- Keep Tidy Mac in the menu bar to watch your free-space trend from then on.
Questions
Why didn’t CleanMyMac free more space?
Cleaners mostly clear caches, logs and leftover junk. On many Macs the biggest space sits in System Data instead: local Time Machine snapshots, iPhone and iPad backups, Xcode and Docker files, AI models and old installers. A cleaner may skip those or leave them unticked, so the disk stays nearly full.
Is Tidy Mac a CleanMyMac alternative?
For storage, yes. Tidy Mac explains and cleans storage, uninstalls apps with their leftovers and watches your free space. It’s $9.99 once for two Macs. It doesn’t scan for malware.
Is it safe to clean System Data?
Parts of it are. Tidy Mac sorts each item into Safe to clear, Worth a look or Kept, ticks only Safe to clear items, never removes Kept ones, and moves everything to the Trash first, so you can put anything back from History.
Can I keep CleanMyMac and use Tidy Mac too?
Yes. They don’t conflict. You can run Tidy Mac to see what System Data is, then decide which subscriptions you still need.
See what’s in your System Data
$9.99 once, on two Macs. Trash first, Undo anytime.