Frhed stands for "Free hex editor". Its features include support for long file names and large editable file sizes (limited only by available system memory). It loads quickly, and includes syntax for describing byte, word, longword, float, and double binary values in text form to be used with find and paste functions.
You can also compare files, search for any combination of text and binary values, manipulate bits, export as Hex, dump to a file or the Clipboard, set bookmarks to easily access offsets in a file, load files partially by dragging them into the window, and apply binary templates for structured information.
In additon, the C++ source code is included.