Clearing app caches safely

An app cache is a store of files the app can make again: downloaded web content, compiled code, graphics data. Clearing it frees space and costs you nothing except a moment while the app rebuilds what it needs. Storage Studio clears only that kind of data. An app's settings, sign-ins, cookies, sessions and history stay exactly where they are, for every app.

How Storage Studio finds caches

It doesn't rely on a list of app names. It looks at what folders contain and where they live:

• Inside an app's data folder, it looks for the well-known cache subfolders that apps use for web, code and graphics caches, and clears only those subfolders. The folder around them, which holds settings and sign-ins, is left alone. Because it goes by folder contents, an app you installed yesterday is covered too.
• In the folder macOS sets aside for caches, which apps use for files they can rebuild, it can offer to clear a single app's cache.
• Known developer and package caches are handled separately. See Developer caches and build folders.

An app's whole data folder is never offered for clearing or moving. Where Storage Studio can't name a part that the app is known to rebuild, it offers nothing and says why: These are apps' own files. Storage Studio only moves the part an app rebuilds by itself — never its settings, sign-ins or history.

%% caption: What Storage Studio checks before clearing part of an app's data
flowchart TD
  A[Folder inside an app's data] --> B{Is it a known rebuildable cache subfolder?}
  B -->|No| C[Left alone - settings, sign-ins and history]
  B -->|Yes| D{Is an app using it right now?}
  D -->|Yes| E[Skipped this time]
  D -->|No| F{Is it a cloud placeholder?}
  F -->|Yes| E
  F -->|No| G[Cleared - the app rebuilds it]

Where caches get cleared

In every case, items an app has open are skipped and tried again next time.

Clearing one app's caches

To clear a single app's cache, open Emergency Space from the More menu (•••) and tick that app's Clear (app)'s cache row, if it's listed. The row explains that the folder holds files the app can rebuild and that Your settings, sign-ins and history are somewhere else and aren't touched. When there's room on your fast drive, a copy is kept first, so you can put it back from the Recycle Vault. If there isn't room, the row says the clear can't be undone.

To change how old cache items must be before Free Up Space clears them, open Settings → Rules and change the age on the Clean app caches rule. That age applies when your external drive is connected and the rules run. If the drive isn't connected, Free Up Space still clears app caches, but without the age limit.

After clearing

The first time you open an app after its cache is cleared, it may take a little longer to start or to show pictures and pages, while it rebuilds what it needs.

See also: Free Up Space · Temporary files you can't see · Auto Rules · Smart Care