If your Mac's storage is filling up and you've started digging into ~/Library, you've probably stumbled across gigabytes tied to iCloud Drive, Dropbox, Google Drive, or OneDrive. A fair question surfaces immediately: does clearing sync cache delete files from these services, or is the local cache truly safe to remove? The short answer is nuanced — a sync cache is not the same as your actual data, but there are real differences between services, and removing the wrong folder can force a re-download of everything you own. This guide breaks down exactly what each major cloud service stores locally, what is safe to remove, and how to do it without losing anything.
What Is a Cloud Sync Cache, Really?
A sync cache is a local copy — either a full mirror or a partial chunk — of files that also live on a remote server. Its purpose is performance: reading a local file is orders of magnitude faster than fetching it from the network every time you open it.
There are two distinct types of local cloud storage on macOS:
- Evictable local copies: Files macOS or the sync client downloaded for access but can re-download on demand. Removing them shrinks your disk but does not touch the cloud copy.
- The only copy: Files you intentionally set to "local only" or that were created offline and haven't yet synced. Deleting these without confirming an upload means permanent loss.
Understanding which category a file sits in is the entire ballgame.
iCloud Drive: Where the Cache Lives and What You Can Remove
iCloud Drive on macOS stores its local files under ~/Library/Mobile Documents/. Third-party apps that use CloudKit write into this same parent directory under their bundle-ID subfolder, e.g. ~/Library/Mobile Documents/com~apple~CloudDocs/ for your main iCloud Drive content.
macOS Sequoia and Tahoe also maintain a separate metadata and chunk cache at ~/Library/Application Support/CloudDocs/ and a daemon-side cache at /private/var/folders/…/com.apple.cloudd/ (the exact hash changes per account). You cannot safely delete the daemon cache manually.
Safe to remove: evicted files
When Optimize Mac Storage is on, macOS automatically evicts files it thinks you don't need locally. The cloud icon with a down-arrow in Finder marks these already-evicted placeholders. They take almost zero space. What does take space are the locally-downloaded copies of files you've recently opened. You can right-click any iCloud folder in Finder and choose Remove Download to evict those copies without touching the cloud original.
Do not remove
Never manually delete anything inside ~/Library/Mobile Documents/ from Terminal unless you are certain the cloud copy is confirmed. Deleting through Terminal bypasses the sync client's awareness and can propagate the deletion to iCloud — and to every other device on your account.
Dropbox: Cache Folder vs. Selective Sync
Dropbox maintains a dedicated local cache at ~/.dropbox/cache/. This folder holds temporary chunks used during uploads and downloads; it is safe to clear when Dropbox is not actively syncing. Dropbox itself clears this cache periodically, but it can balloon to several gigabytes after large file operations.
The actual synced files live inside whatever folder you chose during setup — typically ~/Dropbox/ or a path you specified. Files under Selective Sync that are set to online-only appear as placeholders and use virtually no local space. Clearing the cache subfolder removes only temporary working data, not your Dropbox files.
To safely clear it, quit Dropbox first, then delete the contents (not the folder itself) of ~/.dropbox/cache/.
Google Drive (Drive for Desktop): App Data and Local Files
Google Drive for Desktop stores its index, metadata, and a content cache under ~/Library/Application Support/Google/DriveFS/. This folder can grow large — sometimes 5–15 GB on heavy accounts — because Drive caches file chunks for offline use and keeps a local content database.
Your actual files appear as a virtual drive at /Volumes/Google Drive/ and, unless you've set specific folders to "Mirror," they don't take real disk space. Only mirrored folders write full copies to ~/Library/CloudStorage/GoogleDrive-[account]/.
Clearing the contents of ~/Library/Application Support/Google/DriveFS/ (while Drive for Desktop is quit) forces a full metadata re-sync on next launch, which can take 10–30 minutes but does not delete any cloud data.
OneDrive: Sync Database and Local Copies
Microsoft OneDrive caches metadata and thumbnails in ~/Library/Application Support/OneDrive/ and logs in ~/Library/Logs/OneDrive/. The synced file tree lives under ~/Library/CloudStorage/OneDrive-[account]/ on macOS Sequoia+. Files not yet downloaded appear as online-only and use minimal space. Clearing the Application Support folder resets the client database and triggers a re-scan, but does not affect files on OneDrive.com.
Cloud Sync Cache Size Reference
The table below shows where each major sync service writes its cache on macOS, a typical size range, and whether clearing it is safe without losing cloud data.
| Service | Cache / Metadata Path | Typical Size | Safe to Clear? | Notes |
|---|---|---|---|---|
| iCloud Drive | ~/Library/Application Support/CloudDocs/ |
100 MB – 2 GB | Avoid (use Remove Download in Finder instead) | Evict via Finder; deleting in Terminal can propagate to cloud |
| Dropbox | ~/.dropbox/cache/ |
500 MB – 8 GB | Yes (quit Dropbox first) | Temporary upload/download chunks only |
| Google Drive | ~/Library/Application Support/Google/DriveFS/ |
1 GB – 15 GB | Yes (forces re-index on restart) | No file data lost; slow re-scan on next launch |
| OneDrive | ~/Library/Application Support/OneDrive/ |
200 MB – 3 GB | Yes (quit OneDrive first) | Client DB reset; re-scan required |
| iCloud Drive (mirrored files) | ~/Library/Mobile Documents/ |
Varies — up to 100s of GB | Never from Terminal | Always use Finder or System Settings > iCloud |
How to Safely Reclaim Cloud Sync Cache Space on macOS (Step-by-Step)
Follow these steps in order to reclaim space without risking data loss.
- Confirm everything has synced. Open each sync client and wait for the status icon to show "Up to date" or a green checkmark. Do not proceed if uploads are pending.
- Quit the sync client. Use the menu bar icon to fully quit — not just close its window — so it releases file locks on the cache.
- For iCloud Drive, open Finder, navigate to
~/Library/Mobile Documents/com~apple~CloudDocs/, select large folders you've recently used, right-click, and choose Remove Download. Alternatively, open System Settings > Apple ID > iCloud > iCloud Drive > Options and enable Optimize Mac Storage. - For Dropbox, open Terminal and run:
rm -rf ~/.dropbox/cache/*. Then relaunch Dropbox. - For Google Drive for Desktop, quit the app, then in Finder navigate to
~/Library/Application Support/Google/DriveFS/and move its contents to Trash. Relaunch Drive for Desktop and allow it to re-index. - For OneDrive, quit OneDrive, then remove the contents of
~/Library/Application Support/OneDrive/. Relaunch and sign in again if prompted. - Verify in Finder or Disk Utility that available space has increased before emptying Trash. Only empty Trash once you've confirmed the sync client relaunched without errors.
A tool like Crumb can audit all of these cache locations at once and show what's safe before you delete, which is especially helpful if you have multiple cloud services running simultaneously.
Other Hidden Cloud-Adjacent Caches Worth Knowing
Cloud sync isn't the only source of hidden local copies. Several developer caches behave similarly — large, re-generatable, and safe to clear — but are often overlooked when you're troubleshooting storage. If you're seeing unexplained usage, check:
~/Library/Developer/Xcode/DerivedData/— build artifacts from Xcode; see why Xcode takes up so much space for a full breakdown.~/Library/Caches/— per-app caches that most apps regenerate automatically; safe to clear selectively as described in our guide on what cache files on a Mac actually are.~/.npm/_cacache/andnode_modules/trees — npm/pnpm download caches that can be cleared withnpm cache clean --force.~/.m2/repository/— Maven artifact cache for Java projects; safe to delete, re-downloaded on next build.
The Bottom Line: Cache vs. Data
The distinction that protects your files is simple: a cache is a local convenience copy of something that already exists elsewhere. Your actual data lives on the cloud server and, if the sync client confirmed a successful upload, removing the local cache copy is safe. The risk only appears when you delete files that haven't finished syncing, when you bypass the sync client by using Terminal on directories it actively manages, or when you confuse a mirrored sync folder (where local and cloud are kept identical) with a pure cache folder.
When in doubt, let the sync client tell you the status before touching anything with rm. And if you're looking to understand the broader picture of what's consuming your disk, the full breakdown of what takes up space on a Mac is a good next step.