My Mac Was Down to 32 GB Free. Here's Where 370 GB Was Hiding.

My Mac had 32 GB free on a 1 TB disk. One day later it had 402 GB free. Nothing I use was deleted.

None of it was my own files. It was caches, build output, tools I'd stopped using, and sound libraries I'd never opened. This post lists each one, the command that cleared it, and what I left alone, so I can repeat it next time and you can try it on your own Mac.

I did the cleanup with Claude Code and Mole, a free command-line cleaner for macOS. How I kept the agent from deleting the wrong thing is at the end.

Where the space went

The free-space number doesn't add up exactly: macOS frees some space later (the Trash, Docker's disk image, deleted simulators) and counts in its own way.

The developer leftovers

mo clean (58.6 GB). One run removed 4,837 items. The big ones:

• Xcode DerivedData: 22 GB across 20 projects. Xcode rebuilds it on the next build.
• App caches: 16.9 GB.
• npx cache: 4.8 GB, from every npx some-tool I'd ever run.
• Browser and editor caches: Chrome's service workers (2.6 GB), Puppeteer's browsers (2.1 GB), Notion (2.2 GB), VS Code's webview cache (2 GB).
• 70 simulators for iOS versions no longer installed: 1 GB.

Run mo clean --dry-run first. It lists everything it would remove without removing anything.

Docker (33.8 GB). docker system df showed 58 GB of images, more than half not used by any container. docker image prune -a removes images that no container uses, running or stopped. Docker's disk file doesn't shrink straight away; restarting Docker Desktop releases the space.

uv cache (20.9 GiB). uv keeps every Python package it has ever downloaded. uv cache prune removes the ones no environment uses; it went from 26 GB to 3.1 GB. Mole's preview said it would clean this, but the real run skipped it, so check afterwards.

iOS simulators (15.3 GB). I had four iOS runtimes and kept the newest two: xcrun simctl runtime list shows them, xcrun simctl runtime delete <id> removes one. Then xcrun simctl delete unavailable removes the simulator devices that used the deleted ones.

AI coding tools (~43 GB). I'd tried a lot of them. The apps were gone, but their data wasn't:

• LM Studio models: 13 GB
• Gemini CLI and Antigravity: 15 GB, including three near-identical copies of the same history
• Cursor, VS Code Insiders, Kiro, Windsurf, Hermes: 1–3 GB each

They live in hidden folders in your home folder (~/.cursor, ~/.kiro, ~/.lmstudio, …) and in ~/Library/Application Support. Uninstalling the app doesn't remove them. Check your shell config too: Kiro, LM Studio, Antigravity, Windsurf and Amazon Q had each added lines to ~/.zshrc, and Amazon Q's ran on every new terminal.

The one that surprised me: sound libraries

The biggest item wasn't developer tooling. Logic Pro and GarageBand had about 150 GB of sounds, in two places:

• ~/Music/Logic Pro Library.bundle: 69 GB
• /Library/Application Support/Logic: 61 GB of older sample folders, the location Logic used before
• /Library/Audio/Apple Loops: 7.7 GB
• /Library/Application Support/GarageBand: 6.7 GB

All of it is Apple's free content, and both apps download it again from Sound Library when you need it. macOS counts it as "System Data", which is why that number in System Settings looked so big.

If you remove the old Logic folder, keep Channel Strip Settings and Plug-In Settings: those can hold your own presets. Leave third-party instrument folders next to it alone.

What I kept

• Playwright browsers (10.6 GB) and the Android SDK and emulators (20.5 GB). I still use them; they'd only download again.
• Docker images that containers still use (24 GB).
• node_modules across old projects (27.9 GB). mo purge --dry-run found it; I haven't decided yet. It's the next easy win.
• My own files: a Final Cut library, synced folders, and the Photos library. No cleaner should touch those.

Letting an agent do it without losing anything

An agent that can delete files can delete the wrong ones. These rules kept it safe:

• Preview first, every time. mo clean --dry-run, mo purge --dry-run, docker system df, du -sh. Nothing was removed before I'd seen the list and said yes.
• Trash, not delete, for anything that wasn't a cache. Old tools and app data went to the Trash, so I could check before emptying it.
• Password steps stay with me. The agent never ran sudo. For /Library it gave me the exact command and I ran it in my own terminal.
• When blocked, it stopped. One move was blocked by my permission settings; it told me how to do it in Finder instead of finding another way around.
• Backups of config edits. Before removing Amazon Q's lines from .zshrc, .zprofile and .bashrc, it saved a copy of each.
• Check before blaming the cleaner. VS Code stopped opening halfway through. It turned out VS Code had been running from ~/Downloads, and that folder had gone. Mole's log had no record of removing anything there.

Checklist for next time

1. mo clean --dry-run, read it, then mo clean.
2. docker system df, then docker image prune -a, then restart Docker Desktop.
3. uv cache prune.
4. xcrun simctl runtime list, delete the old runtimes, then xcrun simctl delete unavailable.
5. mo purge --dry-run for node_modules and build folders in old projects.
6. Look in ~ for hidden folders of tools you've uninstalled, and in ~/.zshrc for their lines.
7. If you make music: check Logic and GarageBand's sound libraries.
8. Empty the Trash.