~/Library/Caches is where apps keep temporary data so they do not have to fetch or compute it twice: thumbnails, downloaded images, compiled data, partial web content. It is one of the larger folders in a user Library, and most of it is safe to clear. Most, not all.
What a cache is
A cache is a copy of something the app can get again. Because of that, apps are built to cope when it is missing. After removal, an app typically launches a little slower the first time and refills the folder as you use it.
Which caches are usually fine to remove
- Browser and web content caches. Pages and images download again when you next visit.
- Thumbnail and preview caches. They are regenerated when you browse the files again.
- Caches of apps you rarely use. Nothing reads them, and the app rebuilds them if you return.
- Build and tool caches of developer tools, which rebuild on the next run. See the Xcode cleanup guide.
Where to be careful
- Apps that store offline content in a cache-like folder. Some streaming, reading or note apps keep downloaded items there. Clearing them means downloading again, which matters on a slow connection.
- Anything an app is using right now. Quit the app first, then remove its folder’s contents.
com.apple.*folders. These belong to macOS and its system apps. macOS manages them, and there is little reason to touch them by hand.- Unsynced work. In rare cases an app keeps unsaved or unsynced data in a place that looks like a cache. If an app offers an export or a sync status, check it before clearing.
Remove the contents of an app’s folder, not the Caches folder itself, and never anything in /System/Library/Caches, which macOS protects.
What happens after removal
Expect the app to open more slowly once, to show placeholders while thumbnails regenerate, and to redownload content. The cache then grows again, and how quickly depends on how you use the app. Clearing caches is a way to get space back now, not a permanent one.
Check before you delete
Sort by size to find the big ones: du -sh ~/Library/Caches/* | sort -h lists them in Terminal. A single large folder usually explains most of the space. Space returns to the free-space number only after you empty the Trash, as the Trash guide explains.
How the app approaches caches
The app is in pre-alpha. Its Cleanup section is designed to list caches by app, explain what removing each item does, and leave unticked those where the effect is less clear. Caches, logs and old installers are what the Only safe level ticks by default, and every level requires you to review the list. The scanner today is read-only and cleanup is not built yet.