How to clear Xcode's cache and derived data, and what else Xcode keeps

How we tested: with Xcode 27.0 (27A266a) on an M2 MacBook Air running macOS 27.0.1, on 23 October 2026, we measured each folder Xcode uses and read the help of xcrun simctl, xcodebuild and swift package, without running anything that deletes. Xcode's menus and confirmations were read from Xcode 27's own files. Strata is described as of version 1.0.32, and its Junk Files picture uses a demonstration home folder with stand-in sizes.

What Xcode keeps, and where

The folder named after Xcode in your Caches is not where the space is: on our Mac it held under 300 KB. Derived data and simulators are. And two folders nearby are not caches at all. ~/Library/Developer/Xcode/UserData holds your key bindings, code snippets and themes, so delete only its Previews folder, with Xcode quit, or run xcrun simctl --set previews delete all. ~/Library/org.swift.swiftpm holds Swift Package Manager's settings and the fingerprints it trusts packages by. Never delete ~/Library/Developer as a whole: that takes your archives, your simulators' data and your Xcode settings with it.

On our Mac, a MacBook Air we develop Strata on, the simulator systems were most of it: iOS 27 at 8.1 GB and watchOS 27 at 3.8 GB, 11.9 GB together, which xcrun simctl runtime list prints as 11.1G because it counts in binary units. The sixteen simulators themselves took about 200 MB, never having been used, and Swift Package Manager's cache 64 MB. Derived data was almost empty, because we build with Swift Package Manager, which keeps its build output in a .build folder inside the project instead: about 940 MB for Strata, changing with every build. Xcode 27's documentation, downloaded for offline reading, took another 1.7 GB.

One trap when you measure: du on /Library/Developer/CoreSimulator/Volumes printed 25G here. That folder only holds the simulator systems while they are mounted, so it counts their contents a second time; it is not extra space.

macOS 27's Storage settings has a Developer category for all this too. Its part of macOS lists Xcode Caches, Project Build Data and Indexes, Project Archives, Device Support and Simulator Support, the last with a Manage in Xcode button; we read that from its files rather than seeing it on screen. For caches beyond Xcode's, see our guide to clearing every kind of cache on a Mac.

How to delete derived data

Derived data is what Xcode makes from your source: compiled code, the index behind search and autocomplete, and build logs, along with copies of the packages a project depends on. Xcode 27's own warning says it well: "The first indexing and rebuild of a project after that may be slower." Nothing in it is your work. There are three ways to remove it:

• For one project, in Xcode 27. Open the project and choose Product > Delete Derived Data…. Xcode asks first, and says the project's derived data "will be immediately deleted"; it cannot be undone. The command is new in Xcode 27, and has no shortcut.
• For every project, in Finder. In Xcode, choose Xcode > Settings, click Locations, and click the small arrow after the Derived Data path to open the folder in Finder. Quit Xcode, then move the projects' folders, or everything in it, to the Trash. Or, without Xcode, choose Go > Go to Folder in Finder and enter ~/Library/Developer/Xcode/DerivedData.
• In Terminal. macOS 15 and later have a trash command that moves things to the Trash, so you can still change your mind: trash ~/Library/Developer/Xcode/DerivedData/*. The rm -rf most guides give deletes at once, with no way back.

Quit Xcode before deleting the folder from Finder or Terminal. An Apple engineer said as much in Apple's developer forums: make sure Xcode is quit before you delete things behind its back. And a project can keep its derived data somewhere else, set in File > Project Settings… (Workspace Settings… when a workspace is open), so if the folder looks small, check there.

Product > Clean Build Folder (Shift-Command-K) is the lighter tool. Xcode 27 says it "will delete all of the products and intermediate files in the build folder" of the open project. The index, the logs, package checkouts and other projects' folders stay, so it frees less, but the next build is quicker than after a full delete.

How to remove simulators you no longer use

The systems simulators run are not in your home folder's Library at all. On our Mac, with Xcode 27, xcrun simctl runtime list -v showed them as disk images in /System/Library/AssetsV2, a protected part of macOS that Finder cannot change; Xcode removes them for you. Guides that send you to /Library/Developer/CoreSimulator/Images describe where older versions of Xcode put them. Wherever yours are, that command prints each one's Image Path. Remove them one of two ways:

• In Xcode, choose Xcode > Settings, click Components, and delete the platform versions you no longer test on. Apple's guide to Xcode components covers it. Components also has a section for systems that older versions of Xcode installed.
• In Terminal, see what would go, then remove it:

  xcrun simctl runtime list
  xcrun simctl runtime delete --notUsedSinceDays 90 --dry-run

  Read the dry run's list before you run the command again without --dry-run: a system Xcode has no record of using, as was true of both of ours, may be on it. To remove one system only, give its identifier from the list: xcrun simctl runtime delete followed by it. The command also takes --unusable for systems marked unusable, and --outdated for older builds of a version, such as betas, once a newer build of that same version is available.

If a system you removed does not free its space, or comes back after a restart, that is a known bug: Apple's Xcode 27 release notes list simulator systems that are not completely deleted, and the notes of Xcode 27.2, a release candidate as we write, list it as fixed. Do not try to delete them by hand; macOS does not allow it.

The simulators themselves, each a folder of a device's apps and data, are smaller. A simulator for a system you have removed cannot run any more, and one command clears all of those:

xcrun simctl delete unavailable

Its help says it deletes "devices that are not supported by the current Xcode SDK". If you keep two versions of Xcode, run it with the newer one selected only if you no longer need the older one's simulators.

To remove a simulator you could still use, Xcode 27 has Device Hub, which replaces both the Simulator app and the Devices and Simulators window. Choose Xcode > Open Developer Tool > Device Hub, or Manage Devices… in the run destination menu, then Control-click the simulator in the sidebar, which shows the ones you added or ran on, and choose Remove, as Apple's guide to Device Hub describes. Its apps and data go with it. In Xcode 26 and earlier, use Window > Devices and Simulators. Or run xcrun simctl delete with the simulator's identifier, which xcrun simctl list devices shows.

Device support, archives and package caches

• Device support. When you connect an iPhone to debug, Xcode copies files with symbols for its version of iOS into ~/Library/Developer/Xcode/iOS DeviceSupport, with folders of the same kind for watchOS, tvOS and visionOS, as Apple's guide to operating system symbols explains. Delete the versions you no longer debug on; if you connect a device running one again, Xcode copies it again.
• Archives. Each archive you made for TestFlight or the App Store keeps the debug symbols needed to read that version's crash reports, and nothing makes them again. Apple puts it plainly: "You must retain the Xcode archive for each build of your app you distribute." Delete old ones in Window > Organizer, and keep those of every version people still run.
• Swift packages. In Xcode, File > Packages > Reset Package Caches clears what Xcode keeps of them. In Terminal, swift package purge-cache empties the shared cache of package repositories; with Xcode 26.3 or earlier, run it in a package's folder. In a package, swift package clean deletes its build output, and swift package reset its whole .build folder.

Find all of it in one list

Strata's Junk Files room gathers Xcode's leftovers under Developer Build Data: derived data for each project, the module cache, device support for each version, simulator caches, SwiftUI preview data, simulators whose system is gone, and Xcode's archives. It also finds the build output of your projects' own tools, such as Swift's .build, Rust's target and Flutter's build, by the project file beside each, in your home folder.

The picture at the top shows it. It ticks what Xcode makes again and leaves the rest to you. Each row says when it last changed; point at one to see why it is or is not ticked. Device support and archives start unticked. A project's build output is ticked only when nothing in the project has changed for three months. While Xcode is running, its build data is tagged In use and left unticked, since Xcode may be writing to it. Everything goes to the Trash, and Put Back in Strata returns it. The simulator systems appear in the System Data room instead, since only Xcode may remove them; our guide to System Data after macOS 27 explains where Storage settings counts them. Junk Files and System Data are part of Strata Pro, which every download includes for 14 days.

Frequently asked questions