A Mac disk space visualizer, built into your file manager
macOS says your disk is almost full, then hides the reason behind a blob called “System Data”. FileNav charts any folder by actual size — so you can click the biggest slice and keep going until you find what's really eating your storage.
Included in FileNav and FileNav Pro · macOS 12.4+
Why you can't find it yourself
Apple's storage screen groups your disk by category— Applications, Documents, System Data. Categories sound helpful until you need to act on one. You can't right-click a category. To free space you need a path to a folder, and that's exactly what the panel won't give you.
Browsing manually doesn't work either. Finder hides folder sizes by default, a column of numbers is hard to compare, and the real offender is almost never in plain sight — it's an old iPhone backup five levels deep in ~/Library, or a build cache that quietly grew to 40 GB.
For the longer version of this argument, read What's taking up space on your Mac.
How the visualizer works
Proportion, not numbers
Every item becomes a slice sized to its share of the folder. You don't read a column of numbers — you see instantly which folder is a third of everything.
Click the big slice, drill down
Click an item and FileNav navigates into it and recalculates. Space hogs are always nested, so each click eliminates everything else. Three or four clicks usually lands on the culprit.
Scans in the background
Large folders are measured on a background thread, so the app stays responsive. Selecting a different folder cancels the scan and starts the new one.
Respects hidden files
If you have hidden files shown, the chart includes them — which matters, because the biggest offenders love hiding in ~/Library and other dotted corners.
Frequently asked
How can I see what's taking up space on my Mac?
macOS's storage screen groups your disk into categories like "System Data", which you can't click into or delete. To actually free space you need to see real folders by size. FileNav's disk visualizer charts any folder's contents by size and lets you drill down into the biggest one until you reach the file or folder responsible.
What is "System Data" on a Mac and why is it so big?
System Data is macOS's catch-all bucket for anything it can't classify — caches, logs, old device backups, developer files, and more. It's large because it collects leftovers from many apps. macOS won't tell you where they are, so you need a tool that measures actual folders instead of categories.
Does FileNav's disk visualizer work on cloud folders?
No. It measures local folders. Cloud-only folders such as Google Drive, OneDrive, or Dropbox don't report meaningful local sizes, so FileNav doesn't pretend to measure them.
Is a disk visualizer safe to use?
The visualizer only reads and displays sizes — it never deletes anything. You decide what to remove. A good rule: don't delete a folder you can't name, especially deep inside ~/Library or /System.
Find the 40 GB you forgot about
The visualizer ships with every copy of FileNav. Free for 14 days, no account, no credit card.