This web app is a different take on the typical hex editor/viewer tool. Using this graymap visualization you can easily get a quick overview over binary data and spot interesting structures.
One good example to try out is the Windows Media Creation Tool (MediaCreationTool21H2.exe). If you throw that in you'll quickly see that almost half the data of the 18 MB executable consists of uncompressed bitmaps, which seems kinda wasteful.