Appears to do what is advertised, showing which folders and subfolders are largest, and the size of each. I gave it 4/5 stars because some of the pie chart colors are very dark, and the sizes in those folders are unreadable (black font on very dark). A white font should be used for those dark colors. Also, the folder you choose for analysis is not displayed along with the total size of its contents. And sometimes the final report appears in tiny font with half of the window blank -- but this is corrected by resizing the window slightly. Fast, about 2 min to analyze my 0.4 TB disk contents on a solid state disk (SSD). Alerts you when the analysis is finished. The "Stop" button cancels analysis, which you might want to do since the running app slows other work on your computer. Report window can be enlarged which enlarges the tiny font in the list of largest folders. But long pathnames are truncated, and touching them does not pop up the full name. Clicking on a folder opens a tab for it in Finder (or if a very large application appears in the list, such as VMWare Windows 10, it opens the application -- not a great feature). The "Disk" button actually analyzes only your non-user folders Applications, System, and Library -- not the entire disk. The "My Files" and "Choose" buttons appear to do the same thing, enabling you to choose a folder to analyze, your main user folder by default. My system files totaled 32 GB and my user folder totaled 433 GB, but "Get Info" about my Macintosh HD says 641 GB used -- I don't know how to reconcile 465 vs 641. When I analyzed my entire Macintosh HD, it reported 471 GB. The app has menus on the menubar, but nothing there seems useful. Appears to be recent since copyright year in "About" is 2019. Tested on macOS 10.14.6 Mojave. An alternative app with a much more detailed report and many more options is WhatSize ($30).