A HEX editor lets you view and edit raw values in any computer file. We like HxD for Windows, it’s free but not open source.  It has extensive search features for locating a specific string or value sequence in a huge binary blob. It also opens raw drives, including boot sectors and directory tables, which is helpful for developing microcontroller FAT file systems.

If you’ve never needed to use a HEX editor, why not try it out and feel like a real geek? Download HxD, it runs from a no-install mode so there’s nothing to setup. Drag a file onto HxD, the HEX editor will open and show you the contents. Try a few different files to get a feel for how your operating system stores values in files. A simple notepad .txt file just contains ASCII text values, a Word document looks a lot different. Try a .PNG image file, look at the first few bytes of the file: 0x50 0x4E 0x47, or ‘PNG’.

What’s your favorite HEX editor for your platform?