What free Windows tool is best for analyzing disk usage on a server?

Scanner is very simple and has been useful for quickly seeing which folders are consuming space. However, it hasn’t been maintained for many years, so I’d favor a more actively maintained tool for a customer’s server.

WinDirStat is a solid choice. It’s free, open source, reliable, and provides both a folder-size breakdown and a visual treemap. Scanning can be a little slow on larger disks, but it works well for finding what is taking up space.

FolderSize is another lightweight, portable option if you want something small and simple. It can show folder sizes without the extra visual features of larger tools, which may be enough for a straightforward cleanup.

I’ve used both WinDirStat and TreeSize, and either can do the job. It may be worth trying both briefly to see which interface and scan speed work better for you. Make sure to run the tool with appropriate administrator permissions when checking protected folders.

Be careful with TreeSize Free on Windows Server. The free edition is generally intended for desktop versions of Windows, so server use may require a paid license. Check the current licensing terms before deploying it for a customer.