What is CoreSimulator on Mac, and can you delete it?

By Irshad PC · Published September 25, 2026

Blue CoreSimulator folder icon, ~/Library/Developer. Safe to delete? Partly, with care.

Location: ~/Library/Developer/CoreSimulator
Safe to delete?: Partly, with care Caches are safe to clear. Remove simulators with simctl, not in Finder.

~/Library/Developer/CoreSimulator is where Xcode keeps the simulators you test apps on, plus their caches. The Caches folder inside is safe to empty. The Devices folder holds each simulator’s installed apps and test data, so remove simulators with Xcode or Apple’s simctl tool instead of dragging folders to the Trash. Your projects don’t live here.

What is CoreSimulator?

CoreSimulator is the part of Xcode that runs the Simulator app. The copy in your home folder holds two things that matter:

Devices. One folder per simulator, such as an iPhone 17 or an iPad Air. Each folder has a long ID for a name, and inside it sits that simulator’s whole file system: the apps you ran on it, their data, any photos you dragged in, and its settings.
Caches. Files the Simulator generates for itself and rebuilds when it needs them.

The simulator runtimes, the full copies of iOS, watchOS and other systems that simulators boot, aren’t in here. Since Xcode 14 they’re disk images stored outside your home folder, under the system-level /Library/Developer/CoreSimulator (no tilde), as Tim Sutton documented at macops.ca. Recent Xcode versions can also keep runtimes in /System/Library/AssetsV2, a protected system location discussed on Apple’s developer forums. macOS counts that space as System Data, which our System Data guide explains.

Is it safe to delete?

Part of it is, and the two folders need different handling.

Caches: yes. Quit Simulator first. The top answer to this exact question on Apple’s community forums says the Simulator generates new content there the next time it runs.

Devices: only through Apple’s tools. This folder holds data you created while testing: the apps on each simulator, test accounts you signed into, sample content you added. If you dragged real photos or files into a simulator, those copies live here too. Deleting a simulator erases all of it. Xcode reinstalls your app the next time you run it, but anything you set up by hand inside a simulator is gone.

Don’t delete the whole CoreSimulator folder or the whole Devices folder. That wipes every simulator at once, and Finder can’t tell you which ID folder belongs to which device. xcrun simctl shows each simulator’s name, OS version and state, so you choose what goes.

Why it gets so big

Old simulators stay behind. When you move to a newer Xcode or remove a runtime, the simulators that used it stay in Devices, marked unavailable, until you delete them. Apple’s simctl help describes unavailable devices as ones the current Xcode SDK doesn’t support.
Every app you run on a simulator gets installed inside it, along with whatever data it writes. Big test files multiply across simulators.
Developers on Apple’s forums have reported a bug where a folder named Dead, inside each simulator’s com.apple.containermanagerd caches, keeps growing and survives a restart.

How to clear it yourself

The xcrun simctl commands come with Xcode. Run them as yourself and skip sudo: an Apple engineer pointed out on the developer forums that sudo makes simctl work on root’s simulators, not yours. simctl deletes right away. Nothing goes to the Trash.

Quit Simulator (Device Hub in Xcode 27) and stop any app running from Xcode. Then shut down any simulators still running in the background:
```
xcrun simctl shutdown all
```
See what you have. This lists every simulator with its name, ID and state:
```
xcrun simctl list devices
```
Remove runtimes you no longer target. In Xcode, choose Xcode > Settings and click Components. Under Other Installed Platforms, click the info button next to a runtime, then click Delete (Apple’s instructions). This frees System Data rather than space in this folder. From Terminal, xcrun simctl runtime list shows each runtime’s ID and xcrun simctl runtime delete <ID> removes one.
Delete the simulators whose runtime is gone. If you keep more than one Xcode installed, make sure the one you normally use is selected first, because “unavailable” is judged against the current Xcode:
```
xcrun simctl delete unavailable
```
Delete specific simulators you don’t use, with the ID from step 2. This erases the simulator and everything installed on it:
```
xcrun simctl delete <ID>
```
To keep a simulator but wipe its apps and data back to a clean state, erase it instead:
```
xcrun simctl erase <ID>
```
Empty the caches. In Finder, choose Go > Go to Folder, paste ~/Library/Developer/CoreSimulator/Caches, select everything inside, and move it to the Trash. Leave the Caches folder itself in place. On recent Xcode versions this folder may be small or even empty. Empty the Trash once Simulator runs fine.

Need a runtime back later? Per Apple’s instructions, Xcode shows a Get button next to the run destination when a platform has no runtime installed, and the Components settings can download older versions.

The rest of ~/Library/Developer has other rebuildable folders, like DerivedData and iOS DeviceSupport. See the Library/Developer page and where developer junk hides on your Mac.

What SpaceUp Mac does with it

The Clean tab and Dev Mode, which appears when SpaceUp Mac detects developer or AI tools, include a “Simulator Caches” item that clears only the contents of ~/Library/Developer/CoreSimulator/Caches. It’s deleted directly rather than moved to the Trash, after you approve it on the review screen. Deep Scan lists the whole CoreSimulator folder once it passes 80 MB, labeled “App / SDK data · review”, with a note to manage it through Xcode. It offers Reveal only there, never Move to Trash, because trashing the folder would delete every simulator and anything stored in them. In the direct download, not the App Store version, the Advisor tab runs Apple’s simctl to list runtimes by size, delete the ones you pick and remove unavailable simulators. Those actions are permanent, and Advisor asks you to confirm each one first, naming the Xcode it checks unavailable simulators against when it can (how cleaning works).

Common questions

Will deleting simulators delete my Xcode projects?

No. Your projects stay wherever you saved them. Deleting a simulator removes the copy of your app installed on it, and Xcode installs a fresh one the next time you run on a simulator.

Why didn’t removing a runtime shrink this folder?

Runtimes live outside your home folder, so removing one frees System Data instead. Its simulators stay in Devices as unavailable until you run xcrun simctl delete unavailable.

Is ~/Library/Developer/CoreSimulator/Caches safe to delete?

Yes. Quit Simulator first, and it rebuilds what it needs on the next launch.

Can I delete the Devices folder by hand?

You’d lose every simulator and everything on them in one go, with no way to tell which ID folder was which. Use xcrun simctl delete so you pick what goes.