How to clean your Mac for free — without touching files you actually need

What actually fills up your Mac's storage

The storage bar in macOS (Apple menu > About This Mac > Storage) is often misleading. The "System" category alone can show 40, 60, even 80 GB when macOS itself only weighs around 15 GB. Here's what's actually hiding in there:

• APFS Time Machine snapshots (5–50 GB): macOS stores timestamped local copies of your files that are invisible in Finder. They free up automatically when you need space — but not always quickly enough.
• User and system caches (3–15 GB): every app writes caches to ~/Library/Caches and /Library/Caches. They rebuild automatically — deleting them is completely safe.
• App residues from deleted apps (2–10 GB): dragging an app to the Trash leaves behind data in ~/Library/Application Support, ~/Library/Containers, and ~/Library/Preferences. These never get cleaned up automatically.
• Large forgotten files (10–30 GB): old .dmg installers sitting in Downloads, Xcode DerivedData folders, iPhone/iPad backups via Finder, movies you already watched.
• Duplicate files (5–15 GB): documents, photos, and videos frequently get copied between folders and backed up twice without anyone noticing.
• Downloads folder junk (2–8 GB): the Downloads folder rarely gets cleaned. It quietly fills up with .pdf, .zip, .dmg, and .pkg files that were useful once.
• System and app logs (1–5 GB): ~/Library/Logs and /var/log accumulate journal files indefinitely on some configurations.

Step-by-step cleanup guide

1. Step 1 — Check your storage breakdown
   Open Apple menu > About This Mac > Storage and wait for the bar to fully load. If "System" shows more than 30 GB, you likely have APFS snapshots or large swap files to reclaim first.
2. Step 2 — Empty Trash and clear browser caches
   Cmd+Shift+Delete to empty the Trash. Then: Safari > Develop > Empty Caches (1–3 GB typically), Chrome > Settings > Privacy > Clear browsing data. No risk, immediate result.
3. Step 3 — Find and delete large forgotten files
   MacOptimizers scans all files over 100 MB and sorts them by size. Target old .dmg files, Xcode DerivedData (often 5–20 GB), iPhone/iPad Finder backups, and videos you've already watched. One click shows last access date, another removes the file.
4. Step 4 — Remove app residues properly
   For every app you want to uninstall: use MacOptimizers' uninstaller module instead of dragging to Trash. It removes the app plus all its data in ~/Library in a single pass. See the full uninstall guide.
5. Step 5 — Clean system and user caches
   MacOptimizers identifies the heaviest cache folders (Spotify, Xcode Simulator, Chrome, and cloud sync agents are the usual suspects). Each is rebuilt automatically on next launch. Deleting them causes no data loss.
6. Step 6 — Remove duplicates
   The duplicate scanner finds identical files in Documents, Desktop, Downloads, and Photos using content signatures — not just filenames. Even without touching your photo library, you often recover 3–8 GB from duplicated documents and archives.

What's safe to delete — and what to leave alone

The most common fear with Mac cleanup is accidentally removing something important. Here's the honest breakdown:

• Safe to delete: ~/Library/Caches (app caches), /Library/Caches (system caches), ~/Library/Logs, /var/log, .dmg files in Downloads you've already installed, DerivedData in ~/Library/Developer/Xcode/.
• Check before deleting: ~/Library/Application Support (some apps store important user data here, not just caches), large files in Documents or Desktop.
• Never delete manually: ~/Library/Keychains (passwords), ~/Library/Mail (emails), ~/Library/Photos (photo library database), anything in /System or /usr.

MacOptimizers labels each category and shows the size before you confirm. You're never making blind decisions.