GrandPerspective

WizTree

WizTree is a free disk space analyzer for Windows built by Antibody Software that scans entire hard drives in seconds by reading the NTFS Master File Table directly instead of walking the file system folder by folder. It renders results as an interactive treemap so users can visually spot the largest files and folders on a drive at a glance, then delete or move them without digging through Explorer. Beyond the core treemap view, WizTree includes a duplicate file finder, CSV export for reporting, and support for non-NTFS and network drives via a slower standard scan. The free version is for personal use only; commercial users need a Supporter license priced by organization size, or an Enterprise license for unlimited use across a company.

DaisyDisk

DaisyDisk is a disk space analyzer for macOS that scans internal and external drives, SSDs, HDDs, USB and Thunderbolt devices, network volumes, and cloud storage folders such as Dropbox, Google Drive, OneDrive, and Box to show exactly what is consuming disk space. Results are rendered as an interactive circular sunburst chart, letting users click into folders and drag files to a collection area for deletion, with system and application files automatically protected from accidental removal. The app is built for speed, with the developer claiming a full drive scan takes about 15 seconds versus several minutes in Finder, and it can run with administrator privileges to reveal hidden system files. DaisyDisk is sold as a one-time $9.99 lifetime license covering up to 5 personal Macs, available directly from daisydiskapp.com and on the Mac App Store, with no subscription fees and a 30-day money-back guarantee.

TreeSize Free

TreeSize Free, by JAM Software, is a free disk space analyzer for Windows that shows which folders and files are consuming storage. It presents a treemap visualization of disk usage and can generate PDF reports, making it easy to spot what is taking up space on a drive.

WinDirStat

WinDirStat is a free, open-source disk usage analyzer for Microsoft Windows that scans drives and folders and shows how disk space is distributed across the file system. It uses multithreaded scanning with direct NTFS support and presents results as sortable lists, extension statistics, a Largest Files view, and an interactive treemap that makes it easy to visually spot which folders and file types are consuming the most space. Beyond basic scanning, WinDirStat can detect duplicate files by content, inspect file permissions, and analyze storage tiers, and it supports file operations like opening, moving, or deleting items directly from the results view. It also offers dark mode, Windows Explorer integration, file-system change monitoring, and scan export, and is distributed under the GNU General Public License version 2 (GPLv2) with source code hosted on GitHub.