The Mac Library Folder: What Each Folder Holds

The Library folder in your home folder is where apps keep everything that is not a document you saved yourself: settings, caches, chats, mail, passwords, iCloud files waiting to sync. Finder hides it because most of it should be left alone, and because the folders that look safe to empty sit right beside folders whose loss cannot be undone.

The useful question is never "can I delete Library" but "what is in this one folder, and what happens if it goes". This guide walks through the folders you will see at the top of ~/Library, groups them by what removing them costs, and gives a way to check a folder before you touch it.

Open the Folder

In Finder, choose Go › Go to Folder, type ~/Library and press Return. You can also hold Option while the Go menu is open and choose Library. To see sizes, select the window, choose View › Show View Options and turn on Calculate all sizes in list view.

This is your own Library. /Library at the top of the disk is shared by every user, and /System/Library belongs to macOS and is protected. Everything below is about ~/Library.

Folders That Hold Your Own Data

These folders contain things that may exist nowhere else. Removing them loses data, not just space.

Containers and Group Containers are the two that surprise people most: they look like app plumbing, but apps from the Mac App Store keep their whole library there. Library Containers and Group Containers explain how to tell which app owns each one. Messages and Mail have their own guides for reducing Messages storage and reducing Mail storage from inside the apps.

Folders That Rebuild Themselves

These hold data apps can download or regenerate. Removing them frees space at the cost of a slower first launch, a re-download or a fresh sign-in.

Even here, "rebuilds" is not "free". A cache an app is using while it runs can break that app until it quits, and a large cache refills on the next launch, so clearing it to gain space you will lose again tomorrow is wasted work. Which caches are safe to delete and what to do with log files go through both in detail.

Folders That Hold Settings

These are small, but deleting them changes how apps and macOS behave.

A .plist in Preferences or LaunchAgents named after an app you removed is usually a leftover, and removing leftovers after an uninstall covers how to confirm that. Do not delete a LaunchAgents plist for an app you still use: it is how that app starts its helper.

Folders macOS Manages

Some folders belong to macOS features rather than apps: Biome (usage history for Siri Suggestions and Screen Time), IntelligencePlatform (data Apple Intelligence keeps), Suggestions, PersonalizationPortrait, IdentityServices (iMessage and FaceTime identity), Daemon Containers (background services) and Accessibility. They are usually small, the system expects them, and deleting them trades a little space for odd behavior in the feature that owns them. Leave them alone unless a support article for that feature tells you otherwise.

Developer is the exception on size: it holds Xcode and Simulator data and can reach tens of gigabytes. Archives and simulator data inside it are lost if removed, so use cleaning up Xcode rather than emptying the folder.

Check a Folder Before You Touch It

1. Look at the folder's name. A reverse-domain name such as com.example.app names the app that owns it; search for that identifier with Spotlight to find the app.
2. Check whether that app is still installed and whether it is running. Quit it before moving anything that belongs to it.
3. Open the folder and look at what is inside. Names like Cache, Logs or tmp suggest rebuildable data; names like Documents, Chats, Library or a database file suggest content.
4. Move it to the Trash rather than deleting it outright, open the app, and use it for a while. Empty the Trash only when nothing is missing.

Where Mole Fits

Mole's disk analysis puts a name and one sentence on a folder while you hover over it: what it holds, and where it matters, what removing it costs, such as "Your keychains with passwords, certificates and keys, all lost if removed" for Keychains. Mole carries notes for more than 5,000 known folders, from the top of ~/Library down to app containers, and a folder not in that list is named after its app when its own name proves the owner, such as a bundle identifier of an app installed on the Mac. The largest rows in the side list name their app too.

Analyze does not decide for you: it moves what you pick to the Trash, where it stays recoverable until you empty it. For the parts that are safe to clear, Mole's Clean lists caches, logs and leftovers for review, including cache folders inside some app containers, and never the chats, mail, keychains or cloud files in the first table.

FAQ

Can I delete the whole Library folder?

No. It holds your keychains, mail, messages, iCloud Drive files and app data. Removing it loses data that may exist nowhere else and leaves most apps broken or reset.

Why is my Library folder so big?

Usually because of one or two folders: Containers or Group Containers for chat and media apps, Mobile Documents for iCloud Drive files kept on the Mac, Developer for Xcode, or Caches. Turn on folder sizes in Finder, or use a disk analyzer, and look at the largest folder first.

Is it safe to empty the Caches folder?

Mostly, if the apps are quit first, and most of it comes back as you use the apps. Quit apps before clearing their caches, and expect slower first launches. Folders under Caches that hold downloaded models or offline media are the exception: they cost a full re-download.

What is the difference between ~/Library and /Library?

~/Library belongs to your user account. /Library is shared by every user on the Mac and needs an administrator to change. /System/Library belongs to macOS and is protected.