Diskzy vs WhatSize: an honest comparison
WhatSize is a disk usage utility for the Mac. Its site describes measuring the size of your storage devices and letting you sort, filter and refine the results, with the largest files and folders first and a Finder-style column view for drilling into folders. It also has cleaning tools for log files, downloads, caches, temporary files and unneeded app translations. It costs $14.99, has a 30-day trial, and supports macOS from Big Sur 11 to the current release.
Diskzy answers the same question, what is using the disk, and both tools say they keep up with changes without a full rescan. Diskzy adds an explanation of System Data part by part, a cleanup list aimed at developer files as well as caches and logs, and an uninstaller that removes an app with its leftovers. It needs macOS 15 or later.
| Diskzy | WhatSize | |
|---|---|---|
| Price | Free for 72 hours with everything unlocked, then $9 once for 2 Macs. No subscription. | $14.99 to purchase, $9.99 to upgrade from an earlier version. |
| Trial | 72 hours with everything unlocked. | 30 days. |
| How it shows the disk | Maps the whole disk, with search by name, kind, size or age. | Sizes of files and folders, largest first, with sorting, filtering and a Finder-style column view. |
| System Data | Breaks System Data into named parts, each sized and marked Safe to clear, Look first or Managed by macOS. | Not stated |
| Cleanup | Clean up tab lists caches, logs, Xcode leftovers, project build folders, package-manager caches and old installers, each ticked or unticked with a reason. | Yes. Cleaning tools for log files, downloads, caches, temporary files and unneeded app translations. |
| App uninstaller | Yes, with leftovers. | Not stated |
| Staying current after the first scan | Opens in about a millisecond after the first read and stays current as files change. | Its site says it stays up to date with changes without having to rescan everything. |
| Where deleted files go | The Trash. Nothing is gone until you empty it. | Not stated |
| Requirements | macOS 15 Sequoia or later, Apple silicon and Intel. | macOS Big Sur 11 or later. Its site points owners of older systems to its FAQ. |
When WhatSize is the better choice
Choose WhatSize if you want a longer trial, prefer a Finder-style column view of sizes, want to strip unneeded app translations, or run macOS 11 to 14.
When Diskzy is the better choice
Choose Diskzy if you want System Data explained, cleanup of Xcode leftovers, build folders and package caches with a reason for each, and an uninstaller in the same app.
Details about WhatSize were checked on October 10, 2026 against whatsizemac.com. Prices and features change; check their site for the latest.
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See where your Mac's space went
Diskzy maps your disk, explains System Data and clears what's safe. Free for 72 hours, then $9 once for 2 Macs.
Try Diskzy for free