HxD is a freeware editor supporting disk, memory, and file hex editing, as well as a secure file deletion tool (called a “file shredder” by HxD). HxD’s webpage states the app works on every Windows OS ...
I've been using Hex Fiend, and while pretty good and FOSS, it still lacks in some of the above (especially in UI). Looked at Synalyze It! and while it looks pretty much perfect with some nifty syntax ...