HexEdit allows you to edit binary files, i.e. files that you can't edit with a regular text editor such as the built-in editor. The file's contents are shown as hexadecimal byte values and as ASCII code in two side-by-side blocks. Changes can be made both in the hex table section and in the ASCII section. The usual file navigation with cursors keys, page up&down, home, end, etc. should work as expected. Hexedit is a full-screen console-only editor. I does not work over serial, sorry. The file to edit can be passed in as a command line argument. Press F1 to get help on key bindings.