How to free up disk space on a developer's Mac: the ten folders, in order of size

Storage settings on a developer's Mac shows Applications, Documents, and a grey bar. The grey bar is the work. This is the list of what is in it, in the order it was on my own Mac, with what clearing each one costs.

0. Measure first

du -sh ~/Library/Developer/* ~/Library/Caches ~/Library/Containers/com.docker.docker \
  ~/Library/Application\ Support/MobileSync ~/.npm ~/.gradle ~/.cargo \
  ~/Library/pnpm ~/Library/Caches/Homebrew 2>/dev/null | sort -rh

Everything below is ordered by what that printed for me. Yours will differ.

1. Xcode DerivedData, 39 GB

~/Library/Developer/Xcode/DerivedData. Build output for every project you ever opened. Xcode rebuilds it. Cost: one slow build.

rm -rf ~/Library/Developer/Xcode/DerivedData/*

More on Xcode's folders.

2. iPhone backups, 34 GB

~/Library/Application Support/MobileSync/Backup. Full copies of every device ever backed up here. Cost: nothing for devices that back up elsewhere; everything for a device you no longer have and never restored. Delete from Finder → device → Manage Backups.

Which backups to keep.

3. Device support symbols, 22 GB

~/Library/Developer/Xcode/iOS DeviceSupport. One folder per iOS version you ever attached a device on. Re-downloads on reconnect. Cost: a few minutes the next time you debug on that version.

4. Simulator runtimes and devices, 21 GB

Runtimes are 6 to 10 GB each and old ones are never removed. Cost: one download if you need the version back.

xcrun simctl runtime list
xcrun simctl runtime delete <identifier>
xcrun simctl delete unavailable

Simulators in detail.

5. Docker, 18 GB reclaimable

Inside Docker.raw. Prune frees space inside the VM; the file only shrinks when you resize the disk image in Docker Desktop settings. Cost: images and containers, which re-pull.

docker system df
docker system prune -a

Why Docker.raw never shrinks.

6. App caches, 13 GB

~/Library/Caches. Regenerates. Cost: one slow launch per app. Quit the apps first, and stay out of the neighbouring folders.

What is and is not a cache.

7. Package-manager caches, 10 GB

npm, pnpm, yarn, pip, Gradle, Cargo, CocoaPods, SwiftPM, Go, pub. Each keeps every version it ever downloaded. Cost: one re-download per package on the next install.

Every store and its command.

8. Xcode archives, 6 GB

~/Library/Developer/Xcode/Archives. Cost: the dSYM for that build, which you need to read crash reports from it. Keep every shipped version; delete the rest from Xcode's Organizer.

9. Logs and diagnostics, 3 GB

~/Library/Logs and ~/Library/Logs/DiagnosticReports. Crash reports and app logs. Cost: nothing unless you are in the middle of debugging a crash.

10. Time Machine local snapshots, variable

Not a folder. Hourly snapshots of the whole disk, kept for 24 hours, holding blocks of everything you deleted since. This is why the number does not move after steps 1 to 9.

tmutil listlocalsnapshots /

Why deleting did not free space.

The total

192 GB on my machine, of 225 GB the tools had written. The 33 GB that stayed were archives of shipped builds, the two simulator runtimes I test on, and one iPhone backup I have not decided about.

Where Decruft fits

Decruft runs this list as one scan: every folder above with its measured size, a line on what recreates it, a checkbox, and the Trash instead of rm. The scan is free and needs no license. The commands on this page do the same job if you would rather.