macOS Disk Utilities
GrandPerspective is a small utility application for Mac OS X that graphically shows the disk usage within a file system. It can help you to manage your disk, as you can easily spot which files and folders take up the most space. It uses a so called tree map for visualisation. Each file is shown as a rectangle with an area proportional to the files size. Files in the same folder appear together, but their placement is otherwise arbitrary.
Regarding price from product webpage:
Download GrandPerspective from Sourceforge for free or from the App Store for $2.99. You'll get the same app either way.
So what's the difference? When you get it from the App Store you know that it has passed Apple's review and quality control, you receive automatic updates, you help cover distribution costs and you support further development.
JDiskReport enables you to understand how much space the files and directories consume on your disk drives, and it helps you find obsolete files and folders. The tool analyses your disk drives and collects several statistics which you can view as overview charts and details tables.
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With DaisyDisk you can free up disk space by quickly finding and deleting big, useless files. The program scans any mounted disk and displays it on the sunburst map, where segments mean files and folders, proportionally to their sizes. The map is easy to read and navigate. You can also quickly preview any file and reveal it in Finder to delete.
OmniDiskSweeper is a Mac OS X utility for quickly finding and deleting big, useless files and making space on your hard disks. OmniDiskSweeper scans your disks and highlights the biggest files, so you can determine what's using up your disk space. It's a fast, easy way to find things that are hogging your drive and clear them out so you've got room for the stuff you really need.
2. Clean houseThe free space on the disk and the ordering of the folders are automatically recalculated as you delete the old, space-hogging stuff you don't need anymore.
3. Smarter than FinderSure, you could do this with the Finder, but OmniDiskSweeper makes it easier. Since the directories and files are sorted by size, you get to quickly zoom in on the big files that are taking up all the space—and not worry about the thousands of tiny ones that aren't hurting anyone.
DiskWave is a free utility to help you determine where most of your hard drive space is consumed.
The program scans your hard drive to compute the size of all folders and sub folders. The results are stored in memory, which allows faster navigation than the built-in “compute all sizes” option in the Finder. You can easily identify useless directories and delete them.
WhatSize is a simple tool that allows the user to quickly measure the size in bytes of a given folder and all subfolders and files within it. You would be surprised at how many useless files might be laying around on your hard disks. The files and folders are automatically sorted by size, with the biggest sizes first. While the app is measuring a folder the user can browse the files within that folder and immediately see the size in bytes. Hidden files, cache files, directories will all show up with their corresponding size. This application is similar to the ancient NeXTSTEP, DarkForest. Once the measuring of a folder has ended the user can also view the information by filtering for particular file sizes or types. The user can also move unwanted files and folder in the corresponding Trash bin similar to the Finders Delete button.