What Are Junk Files on Mac - Find and Delete Junk Files Safely

What are junk files?

"Junk files" isn't a technical macOS term. It's a broad label people use for files that:

Examples include cache files, log files, installer packages (DMG/PKG), temporary browser data, items sitting in the Trash, leftover files from deleted apps, etc.

Common types of junk files

Junk files are of different types. You use your computer to do different tasks and run diverse programs on your device, creating different kinds of junk files.

So, how do you identify the junk data on a PC or Mac? Here we've summarised the common types of junk files and given you corresponding examples. 

System & user cache files

They are also called temporary system files. System caches are used to load the core extensions of your operating system for a stable and quick startup, identify the accuracy of the user information, or ensure essential functions of the apps work. They are outdated once their job ends.

Location (user cache): ~/Library/Caches

Purpose:

Safe rule: You can delete files inside ~/Library/Caches. macOS and apps will rebuild the required cache files automatically.

Do NOT delete: /System/Library

Useless app installers 

Usually, after an app installation, the downloaded app installer (the DMG file or PKG file) is no longer useful, and the system will always prompt you to delete it. If you ignore that, the old app installers will accumulate on your Mac.

Location: Downloads folder

Safe to delete: Old DMG, PKG files

Browser data

The browsing history, cookies, and other site data are left even if you've closed the browser tab. They are saved in your browser folder to make your next visit quick on the same page. In addition to that, they are useless but may lead to your browser, such as Mac Safari is not working.

Location:

Clearing browser data:

Safe, but understand the tradeoff - boost the browser, but lose the history of the webpages you've recently visited.

Files in the Trash 

The files moved to the Trash bin are meaningless to you. They still occupy your storage space until permanently deleted, as they are actually stored in the Trash folder on your computer.

Location: ~/.Trash

Emptying Trash is completely safe — as long as you are sure you no longer need those files.

Duplicate files

You may mistakenly save some duplicate files on your computer. They are just a copy of the original file and are redundant.

Leftovers of deleted apps

Every app has a folder to store the settings data and other files. Sometimes, the preferences folder of a deleted program still stays on your computer and takes up disk space.

Location:

Apart from the mentioned types, many other files can be divided into the junk file category. In some users' eyes, once the data is useless but occupies storage space on their computers, it is a junk file.

When do junk files actually become a problem?

Junk files become worth cleaning when:

They do not automatically cause crashes or serious system instability. In most cases, they simply consume storage.

Is it safe to delete junk files?

Yes, it is safe to delete junk files.

There is no concern about cache files, leftovers of deleted apps, duplicate files, etc. They won't play a role in your later work.

But for some specific files, they can be regarded as junk files at the current time, but may be useful for you in the future. For example, the browsing history of a webpage can help your second visit if you forgot its URL.

Safe to delete:

Avoid deleting:

If you're unsure, don't delete manually.

Where are your junk files?

The junk files are scattered on your device and are of different kinds. How do you find them? You can find out the files in every category and judge if they are junk. 

To find the junk files, you need to:

• Open your downloads folder to check if there are useless download files and useless app installers.
• Open the system folder or library folder (~/Library/) to check the Caches folder, leftovers of deleted apps, and broken app settings.
• Launch the Trash or Recycle bin of your computer to check the deleted files.
• Go to all the browsers on your device to check the history and cookies they saved.

How to clean up junk files on your Mac?

Finding the junk files on your Mac is not an easy job, let alone cleaning them up one by one. 

Manually clean up junk files on a Mac

But if you want to remove junk files by yourself, you can delete them by category.

• How to clear cookies on Mac?

• How to clear the cache on Mac?

• How to delete duplicates on Mac?

• How to delete downloads on Mac?

Notably, cleaning up junk files by hand may make mistakes and lead to data loss. So, be careful when removing junk files.

Clear junk files on Mac with a professional Mac cleaner tool

Alternatively, you can choose a junk file cleaner to help you do this complicated job. 

iBoysoft Cleaner is such a tool. It utilizes the self-designed AI-driven scanning feature to quickly identify different types of junk files on a Mac and list them by categories.

With it, you can delete the app cache, user log, browser cache, old downloads, system junk, and other junk files with one click.

Here's how:

FAQs