Independent guide
An Independent Guide to SpaceSniffer
SpaceSniffer is a portable Windows disk utility from Umberto Uderzo of Uderzo Software. It draws folders and files as a treemap so large items are easy to see. This page explains the ideas behind that view, using behavior the developer has published.
Updated October 21, 2026. Windows menus can differ by version and by settings on the PC.
What the software does
The product page describes a scan of a disk that produces a treemap: each folder or file is a shape sized to its occupation. Larger on screen means larger on disk. The developer credits the treemap idea to Ben Shneiderman and presents the tool as freeware, with donations welcomed. The features list adds that it is portable, that it does not require installation, and that settings live in an XML file rather than in a pile of registry entries.
The same list says you can navigate while a scan is still running, open more than one view of a scan, and ask for a closer scan of a zoomed area without waiting for the rest of the disk. If files change underneath the scan, the view is meant to stay in step, and changed elements blink. Blinking means “this changed,” not “delete this.”
Treemap navigation
The product page distinguishes two gestures. A single click selects an element and shows more detail for it. A double click zooms a folder so it fills the view, which reveals smaller items that were hard to see. The features list says zoomable elements let you navigate like a web browser. This guide does not invent names for toolbar buttons. If you need a control that is not described here, check the copy you are running or the developer’s site.
Single click
Selects a rectangle and reveals the detail the product page describes. The rest of the drive remains in context.
Double click
Zooms that folder to the whole view. Smaller files and folders inside it get room to be labeled.
Reading scan results
Follow the largest rectangles if you are trying to learn why free space disappeared. A rectangle can be a folder full of children or a single large file, and the product page treats both as elements. Files are drawn differently from folders so you can tell when you have reached a file.
The published description ties rectangle size to disk occupation. It does not, in the pages used for this guide, spell out a separate “size” versus “size on disk” switch. Compare the scan with the used-space figure in Windows if you need the volume’s own number. Permissions, hard links, and cloud placeholders can still create a gap. Those limits are explained in the disk space analyzer guide.
Folder expansion
Zooming is how you expand a folder in this kind of view. After a double click, the folder is the new frame. Going back returns to the wider picture. The features list also says a display can limit how deeply rectangles are nested so the screen does not turn into noise, and that you can refine a zoomed region with a secondary scan while the broader scan continues.
File size interpretation
A large rectangle is a large recorded occupation, not a recommendation. Windows, a game, a video project, and a disk image are all legitimate ways to fill a drive. Right-click, according to the features list, can open the standard Windows menu for that file or folder. That menu is Windows acting on the item. It is still your decision, and system folders remain a poor place to experiment.
Filtering
The product page shows a filter field. You type a condition and press Enter. A pattern such as *.jpg is the published example for limiting the view to JPEG names. A leading pipe, as in |*.jpg, is the published example for excluding those names. An age example on the page is >2years. A combined example mixes type, size, age, and a tag exclusion: *.jpg;>1mb;<3months;|:yellow.
This guide does not restate a full filter grammar. The developer’s site is the reference for every operator. A filter changes what is drawn. It does not delete the files that disappear from the view.
Tags
Four tag colors are documented. The product page says you can hover a file and press Ctrl+1 to mark it red, and that yellow, green, and blue have keys as well. It does not need those other key numbers repeated here, because this guide will not guess them. Tag filters in the published examples include :red for red-tagged files and :all for tagged files. The features list calls the tags temporary. They are marks inside the tool, not a change to the file on disk.
Reports and extra data
An export module can write a text report, and the developer says the report layout can be customized. This guide does not name a menu for that command. The features list also says scans can include NTFS alternate data streams. Those streams are extra data attached to a file. Explorer does not feature them in an ordinary size column. They are usually small. Including them makes a scan more complete. It rarely explains a drive that is suddenly full.
Common misunderstandings
Misunderstanding
SpaceSniffer is part of Windows, or this website is its official support desk.
Clearer view
It is a third-party freeware tool. This site is an independent explanation and does not run or support the program.
Misunderstanding
The biggest Windows rectangle is clutter that should be deleted.
Clearer view
The operating system is large. Identify the folder before you change anything, and prefer Windows cleanup screens for system leftovers.
Misunderstanding
A filter or a tag removes files.
Clearer view
Filters hide or show elements in the view. Tags mark them temporarily inside the tool.
Misunderstanding
The sample treemap on SpaceSanifferDo is a SpaceSniffer scan of your PC.
Clearer view
Our map is simulated teaching data. It never reads the computer you are using.
Where to read the developer’s own pages
The product description is the SpaceSniffer product page on uderzo.it. A shorter feature list is the features page. Both sites are operated by the developer, not by SpaceSanifferDo.
For a side-by-side look at Windows views and treemap tools, use the disk analyzer comparison. To practice area and nesting without any desktop program, open the visualizer guide or the simulated treemap.