Developer caches and build folders

If you write software, your Mac collects caches from package managers and build tools that can grow very large. Storage Studio recognises the common ones. It clears the caches your tools download or build again on demand, and offers to move large developer data you'd rather keep, such as old simulators and archives, to your external drive with a shortcut left behind.

It only creates rules for tools you actually have. On a Mac without them, none of this appears.

What it recognises

Caches that are cleared (they rebuild on demand):

• package-manager caches for npm, pnpm, Yarn, Bun, pip, Composer, Cargo, Go, Deno, Homebrew and CocoaPods;
• the Xcode build cache;
• downloaded browsers used for testing, from Puppeteer and Playwright;
• the Gradle cache, simulator caches, the Maven repository and NuGet packages. These are suggested for your approval first rather than applied automatically.

Large developer data that is moved, not cleared (suggested for your approval):

• Xcode archives and iOS device support files;
• iOS simulators and Android system images;
• Docker's data.

Storage Studio also notices large folders called cache inside other tools' hidden folders in your home folder, and suggests them for your review even if it doesn't know the tool by name.

The workflow

%% caption: How developer caches and data are handled
flowchart TD
  A[Auto Rules looks at your Mac] --> B{Is it a known cache that rebuilds itself?}
  B -->|Yes, safest kind| C[Rule applied automatically: cleared once old enough]
  B -->|Yes, less certain| D[Suggested - you approve or dismiss]
  B -->|No, large reusable data| E[Suggested move to your external drive]
  E -->|Approve| F[Moved, with a shortcut left behind]
  C --> G[Runs with Free Up Space and Smart Care]
  D -->|Approve| G

1. Open Auto Rules. Click Auto rules on the Home screen, or go to Settings → Rules → Auto Rules → Review…. Storage Studio lists what it found on your Mac. See Auto Rules.
2. Check what's already applied. The safest caches appear under Applied automatically, unless you've turned on Suggest only — never apply automatically. Each is cleared once its contents are old enough, between 14 and 30 days depending on the cache.
3. Approve what you want moved. Large developer data appears under Suggested — needs your approval, with its size and the reason, for example Large developer data — moved to your external drive and linked back, so your tools keep working. Click Approve for the ones you want, or Dismiss.
4. Let it run. Approved rules run with Free Up Space, with Smart Care, and in the daily automatic run if you have one. Moves need your external drive connected.

Clearing developer caches straight away

Smart Care adds a Clear developer & package caches step when the main package-manager and build caches (Homebrew, CocoaPods, pip, Yarn, npm, pnpm, Cargo and the Xcode build cache) hold at least 50 MB. That step clears them whatever their age, skipping anything a running tool has open. Your tools download or rebuild what they need next time, which can make the next build or install slower.

Things to keep in mind

• Moved developer data stays usable through its shortcut only while the external drive is connected. If you work away from the drive, don't move the simulators or toolchains you use daily.
• A move only takes items that are older than the rule's age, and skips anything a running tool has open, so work in progress stays where it is.
• You can change a rule's age in Settings → Rules, and stop one with Dismiss in Auto Rules.

See also: Clearing app caches safely · The shortcut left behind after a move · Rules: moving folders automatically · Moving folders safely