Diskzy vs GrandPerspective: an honest comparison
GrandPerspective is a free, open source disk usage viewer released under the GNU General Public License. It draws a folder or a whole disk as a treemap, lets you filter or mask files, save a scan to view again later, and rescan to compare before and after a cleanup. It is free from SourceForge or $2.99 on the Mac App Store, and its site says you get the same app either way.
Diskzy is a paid, closed source app that covers more ground. As well as mapping the disk it explains what is inside System Data, suggests what to clean with a reason for each item, and uninstalls apps with their leftovers. Its map stays current as files change instead of needing a rescan.
| Diskzy | GrandPerspective | |
|---|---|---|
| Price | Free for 72 hours with everything unlocked, then $9 once for 2 Macs. | Free from SourceForge, or $2.99 once on the Mac App Store. |
| Source code | Closed source. | Open source under the GNU General Public License. |
| Disk map | Maps the whole disk. | Treemap of any folder or disk, with filters and saved scans. |
| System Data | Breaks System Data into named parts, each sized and marked Safe to clear, Look first or Managed by macOS. | Not stated |
| Cleanup suggestions | Clean up tab lists caches, logs, Xcode leftovers, build folders and more, each ticked or unticked with a reason. | None. You find and delete files yourself from the view. |
| App uninstaller | Yes, with leftovers. | Not stated |
| Staying current after the first scan | Stays current as files change. | You refresh or rescan a view to see changes. |
| Where deleted files go | The Trash. Nothing is gone until you empty it. | Files and folders can be deleted from the view. Whether they go to the Trash is not stated on its site. |
| Requirements | macOS 15 Sequoia or later, Apple silicon and Intel. | Version 3.8.1 needs macOS 14 or higher, Apple silicon or Intel. Earlier releases support older macOS versions. |
When GrandPerspective is the better choice
Choose GrandPerspective if you want a free or open source tool, only need to see what is taking space, or run an older macOS version that its earlier releases still support.
When Diskzy is the better choice
Choose Diskzy if you also want System Data explained, cleanup suggestions with reasons and an uninstaller, and a map that updates on its own.
Details about GrandPerspective were checked on October 10, 2026 against grandperspectiv.sourceforge.net. 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.
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