WizTree

What WizTree measures

WizTree answers the oldest maintenance question on Windows: what is using all the space. It does so by a route that explains its speed. Rather than walking directories and asking the filesystem about each file, it reads the master file table directly, the index NTFS already maintains, and reconstructs the folder tree from it. A scan of a multi-terabyte drive therefore completes in seconds rather than minutes, and the result is presented as a sortable list of files and folders, a proportional treemap where every rectangle is a file, and a hierarchical tree. The file view can be filtered by extension, and the whole dataset can be exported as CSV for spreadsheet analysis or comparison between scans.

How the workflow fits together

A portable ZIP and a conventional installer are both published; the portable build needs no installation, which suits a one-off look at someone else's machine. Start the scan on a drive or a single folder, then read the treemap: large rectangles are the immediate answers, and clicking one drills into the folder that contains it. The file-type summary shows whether the space is in video, virtual-machine images, or thousands of small temporary files. Selecting a file and opening its location in Explorer or deleting it are one action away, and the CSV export lets two scans be compared so you can find what grew between them. Files can also be copied to the clipboard as a path list, which is convenient for a scripted cleanup.

Configuration, limits and trade-offs

The scanning engine needs a local NTFS volume to read the master file table; network shares and non-NTFS filesystems fall back to ordinary directory traversal and are correspondingly slower. Reading the index is also the reason the tool sees files that the ordinary API sometimes misses but not the contents of anything: it reports sizes, it does not show what is inside a file. Deletion is permanent or to the recycle bin depending on your choice, and there is no undo, so the treemap should be treated as evidence before the delete key is pressed. The licence is the other practical limit: the free tier is for personal use, and installing it across a company requires a distribution licence, which the vendor sells separately.

Who should choose something else

WinDirStat and similar analysers are open source and licensed without a personal-use restriction, which matters in a commercial setting where the WizTree licence is not appropriate. A machine that needs regular reporting rather than occasional investigation is better served by a monitoring agent that records growth over time. And when the real problem is not disk space but thousands of small files slowing a backup or a copy, a file-count-oriented analysis or a backup tool's own statistics will answer the question more directly than a size-based treemap.