Fast Explorer is described as 'Handy Windows shell context menu editor that allows you to add new menu items, cascaded menus, customize menu bitmaps and hint text, and even clean up context menu items and remove shell extensions of files and folders' and is a context menu manager in the os & utilities category. There are more than 10 alternatives to Fast Explorer for Windows, File Explorer and Mac. The best Fast Explorer alternative is Shell, which is both free and Open Source. Other great apps like Fast Explorer are FileMenu Tools, Menuist, ShellExView and ShellMenuView.
Cannot edit / add context menu entries freely. Just add some context menu commands as designed by the authors. Most likely to become a commercial product soon.