Free Hex Editor "frhed"

frhed is a basic free hex editor available at: http://www.kibria.de/frhed.html

This is _not_ the malware with the same name.

Instead, it's free software released under the GPL and includes source. From the homepage:

* Open Source! Distributed under GNU General Public License
* Native 32 bit Windows application: long filenames supported, editable file size limited only by available system memory.
* Small program size (ca. 100K), loads fast.
* Cut, copy & paste binary values.
* Syntax for describing byte, word, longword, float and double binary values in text form to use with find and paste functions.
* Directly enter hexadecimal values or text in main window (overwrite or insert).
* Compare files.
* Find/Replace any combination of text and binary values.
* Bit manipulation.
* Export as hexdump to file or clipboard.
* Automatically adjust bytes displayed per hexdump line to window width, or set bytes per line manually.
* Choose font size, character set (ANSI or OEM), colors of text and background.
* Intel or Motorola binary format.
* Can be used as "Send to"-Target.
* Set bookmarks to easily access offsets in the file.
* Load files partially.
* Drag and Drop.
* Apply binary templates for structured information.
* Hard disk sector read access.
* Cryptography support.
* C++ source code is included (written using Microsoft Visual C++ 4.0, does not use MFC).
* No registration fee required.