System & FinderFree Up Space
How to clear System Data on Mac
You can't clear System Data on a Mac directly, because macOS manages it. Open System Settings › General › Storage, empty the Trash and follow the recommendations, and macOS clears its own caches when space runs low. Free Up Space removes app caches, Xcode build files, npm and Gradle caches and old Downloads, some of which count as System Data.
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One of 68 fixes in MrFixable. Lifetime license, no subscription. Updated October 22, 2026. Works on macOS 14.2 Sonoma and later. Checked on macOS 26 Tahoe.
What Free Up Space does
The problem
When your startup disk fills up, System Settings › General › Storage shows big categories and a few recommendations, and System Data is often one of the biggest. You can't open it or clear it there, and the app caches and tool downloads, such as npm's, that grow to many gigabytes aren't listed. Deleting those by hand means knowing which folders are safe to touch.
With Free Up Space
Free Up Space lists what's safe to remove, with the size of each, and you tick what to clean. One click frees the space and tells you how much.
- Safe things ticked firstApp caches, Xcode build files (DerivedData), old iPhone and Watch debug files, and the npm and Gradle caches start ticked. Apps and tools make them again when they need them.
- The rest is your choiceDownloads older than 30 days, the Trash and, if you have Xcode, the iOS simulators are listed too, but unticked. Old downloads go to the Trash, so you can still get them back.
- Careful with what's in usemacOS's own caches and the caches of apps that are open are skipped. For debug files, the newest one for each kind of device is kept.
- See where the space wentThe page shows how much is free on your Mac, the size of each thing on the list, and the biggest app caches by name.
Good to know
It cleans only the things on its list. It won't clear everything macOS counts as System Data, such as system files and logs that macOS manages itself.
Downloads are only looked at when you tick them, because macOS asks your permission for that folder. Emptying the Trash goes through Finder, and macOS asks once whether MrFixable may control Finder.
Caches and build files are deleted for good, and an emptied Trash can't be undone. The next Xcode build of each project takes longer.
Nothing runs in the background. Sizes are checked again each time you open the page.
Questions
How do I clear System Data on a Mac?
Clear the parts you control, since macOS manages the rest. 1. Choose Apple menu › System Settings › General › Storage. 2. Empty the Trash and turn on the recommendations. 3. Remove app caches, with Free Up Space or by hand in ~/Library/Caches. 4. Restart your Mac so macOS can clear temporary files.What is System Data on a Mac?
System Data is the storage category for files that don't fit Apps, Documents, Photos or the others in Storage settings. It mostly holds system files: caches and logs, temporary and virtual memory files, and app support files and plug-ins. macOS manages it, so its size goes up and down.How do I reduce Mac System Data?
Remove the caches and leftovers you're allowed to remove. 1. Open Free Up Space in MrFixable. 2. Keep the ticked items: app caches, Xcode build files and package caches. 3. Click Free Up Space. 4. Restart. Then check System Settings › General › Storage again to see how much System Data changed.My Mac storage is full: how do I free up space?
Start with Storage settings. 1. Open System Settings › General › Storage. 2. Turn on Store in iCloud, Optimize Storage or Empty Trash Automatically. 3. Click the Info button next to a category, such as Applications or Documents, to see and delete large items. 4. Empty the Trash, since trashed files still take space.What should I do when my Mac storage is full?
Delete what you don't need, then empty the Trash. 1. Follow the recommendations in System Settings › General › Storage. 2. Move big files you rarely use to an external drive or iCloud. 3. Clear app caches, which Storage doesn't list, with Free Up Space. It shows the size of each first.Why does my Mac storage keep filling up?
Apps and tools keep adding caches, downloads and build files, and the Trash keeps what you delete until it's emptied. To stop it: 1. Turn on Empty Trash Automatically in System Settings › General › Storage. 2. Clear old Downloads. 3. Run Free Up Space now and then to clear caches that grew back.
Sources
Guides
- How to clear the cache on a Mac safelyHow to clear the cache on a Mac: app caches in your Library folder, Safari and Chrome caches, what not to delete, and a safe way to do it all in one step.
- How to clear System Data on a Mac, and what's safe to removeHow to clear System Data on a Mac: what System Data is, why Storage settings won't let you delete it, and the safe steps that shrink it. Free 14-day trial.
- Mac storage full? See what takes up space and free it upMac storage full? How to see what takes up space in Storage settings, which files to delete first, why storage keeps filling up, and how to free up space.
- How to delete apps on a Mac: every way in macOS TahoeHow to delete apps on a Mac in macOS Tahoe: from Finder, from Storage settings or with the app's own uninstaller, and how to remove the files apps leave.
- How to uninstall apps on a Mac completely, without leftoversTo uninstall an app on a Mac, quit it and drag it to the Trash. Where its settings, caches and data stay behind, how to remove them by hand, and a one-step way.
Compare
- Free Up Space vs CleanMyMacCleanMyMac is MacPaw's all-in-one Mac cleaner, sold as a subscription from $3.33 a month on its site. MrFixable covers two of its jobs: App Uninstaller removes apps with their leftovers, and Free Up Space clears app caches, Xcode build files, old Downloads and the Trash. Both come with MrFixable's other fixes for $19.99 once.
- Free Up Space vs OnyXThe best OnyX alternative for Mac depends on what you use OnyX for. OnyX is a free utility that checks your disk, rebuilds indexes, clears caches and changes many hidden settings. MrFixable covers the everyday parts as simple switches, such as Free Up Space, App Uninstaller, Show Hidden Files and Screenshot Settings, for $19.99 once.