What Is WinDirStat and How to Use It: Free Open Source Disk Usage Analyzer with Treemap

The C drive is full again, and scrolling through File Explorer reveals nothing that accounts for tens of gigabytes. The storage tool built into Windows gives only a broad outline. To dig down to a specific folder, a dedicated utility helps. WinDirStat does this job. It scans a drive once, then lays the directory sizes out as a colored rectangle map, so the biggest block tells you where to look first, and finding large files becomes visual.

What Is WinDirStat

WinDirStat, short for Windows Directory Statistics, is a free, open source disk usage analyzer and cleanup aid, with its repository at windirstat/windirstat under GPL-3.0 or later. On launch it reads the whole directory tree once, then presents the result in three views: a directory list sorted by size, a Treemap of colored rectangles, and a summary by file extension. Which file type eats the most space and which folder is fattest become obvious at a glance. It supports Windows 7 through Windows 11 and every version of Windows Server, and it is a common first stop for the question of why a disk is full. If the symptom is a system that stutters with the disk pinned at 100 percent, that is a different problem, and Windows Disk at 100 Percent and Active Time Full is a better match.

Features

• Disk scanning. Covers a whole drive, a single folder, a network share, or an attached MTP device, with pause, resume, and an accelerated NTFS scan.
• Treemap view. Draws colored rectangles whose area tracks file size, so large files stand out across the screen.
• Extension summary. Totals space by file type, doubling as a legend and a ranking, which shows whether video or cache is the culprit.
• Duplicate finding. Uses a configurable hash to locate repeated files, with cloud-file protection to avoid deleting placeholders.
• Cleanup aids. Opens, moves, or deletes files directly, and can call system cleanup tools, apply NTFS compression, or deduplicate hard links.
• Report export. Saves scan results, duplicates, or permission details to CSV or JSON, and supports command-line calls.
• Light and portable. The installer is small, scanning is read-only, and closing the program leaves the system alone.

It answers where the space went. To locate a file by name at speed, pair it with Find Any File Instantly on Windows with Everything.

How to Use

1. From GitHub Releases grab the 64-bit MSI WinDirStat-x64.msi and run it, or install with winget install -e --id WinDirStat.WinDirStat.
2. On launch, tick the drives or folders to scan, then confirm.
3. When it finishes, the size-sorted list sits on the left, the Treemap at upper right, and the extension summary below.
4. Click a rectangle in the map and the list jumps to its directory.
5. Right-click a file to open, delete, or inspect its properties. Confirm it is no longer needed.
6. To keep a snapshot, save results as CSV or JSON from the File menu.

A full scan reads heavily from the disk, so run it when idle. Protected folders need administrator rights, through Run as administrator or the File menu's Run Elevated command. Scanning one folder is faster than the whole drive.

Supported Platforms

Network shares and MTP devices can also be scanned, though the speed depends on the connection. Caching all three views from a single pass means switching between them does not reread the disk, and the program stays responsive. The small installer runs on older hardware too, including machines still on Windows 7.

Pricing

WinDirStat is released as GPL free software and is free for personal and commercial use, with rights to use, modify, and redistribute it. There is no subscription, no advertising, and no paid tier. Get it from the official GitHub Releases page, Microsoft Store, or a package manager, since third-party sites may bundle an installer. It asks for nothing beyond that, runs on demand, leaves no background process, and changes no system settings.

Use Cases

• C drive rescue. Find temp files, caches, or one application folder that grew out of hand over months of use.
• External drive cleanup. See which few folders are largest before deleting anything from a full backup disk.
• Video archive. Confirm with the extension summary that tens of gigabytes of footage are the cause.
• Duplicate tidy-up. Turn on duplicate finding to clear repeated backups scattered in several places.
• Snapshot handoff. Export the scan to CSV for a colleague or for your own records.
• Regular checkups. Scan the system drive each quarter to catch abnormal log growth early, before it fills the partition.

Deletion cannot be undone, so back up important data before cleaning. That is the one rule worth keeping in mind with this kind of tool.

How It Works

WinDirStat is a long-standing open source project maintained by the community, with its code public on GitHub under GPL-3.0 and changes gathered through issues and pull requests. There is no company behind it and no commercial pressure, so the feature set has stayed restrained over the years, focused on doing one thing well: scan once, show clearly, delete accurately. A single pass caches all three views, so switching between them does not reread the disk. A command-line call exists alongside the graphical interface for use in maintenance scripts. Because it does not earn money from the tool, there are no ads and no uploads, and scan data stays on the local machine, which matters to anyone who cares about privacy.

Conclusion

When a disk fills up, do not start deleting at random. Run WinDirStat once, see where the space actually went, then act. The colored map plus the extension summary usually pinpoints the exact files, and the CSV export keeps a record. Back up before deleting and download from an official source, and it is a tool that simply works. For a free utility, the clarity of the colored map is hard to overstate.

Project https://github.com/windirstat/windirstat Website https://windirstat.net/