Distinguish cache from data
~/Library/Caches generally holds user-level caches, while apps may store downloads, databases, and offline content under Application Support or Containers. Those locations should not be batch-cleared as cache.
Browser assets, image thumbnails, and compiler cache are commonly rebuildable. Mail databases, chat history, photo libraries, and project media are user data. Even a name containing cache needs context from the app.
Prefer the app's own cleanup control
Browsers, media apps, and developer tools often include a command to clear cache or manage downloads. The app can update its indexes at the same time, making this safer than removing folders behind its back.
Quit an app before touching its cache so it is not writing concurrently. A slower first launch afterward is expected while content is rebuilt.
Use a reversible manual order
Back up important data and close related apps. Select only cache directories whose owner and reproducibility you have confirmed, and move them to Trash instead of deleting permanently. Reopen the app, test important actions, and empty Trash later.
Never remove the entire ~/Library, modify /System, or disable system protection to gain access. If a cache immediately grows back, the app needs it; repeated deletion offers no lasting benefit.
When cache cleanup is worthwhile
Targeted cleanup helps when a cache grows abnormally, an app is malfunctioning, or free space is critically low. When capacity is healthy, frequent clearing mainly creates more downloads and rebuilding work.
Measure first to find the cache that is actually large. Diskly separates rebuildable suggestions from items that need review and exposes real paths before action, keeping cache cleanup from becoming blind deletion.
Understand first, clean second
Diskly scans locally on your Mac, maps real usage in a treemap, and keeps every cleanup suggestion reviewable.
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