Hex editors

Beye
BEYE (Binary EYE) is a multiplatform, portable viewer of binary files with a built-in editor that functions in binary, hexadecimal and disassembler modes.

bvi
bvi is a screen-oriented computer program used to edit binary files.

Climacs
Climacs is an open source text editor written in Common Lisp that is similar to GNU Emacs and is released under the GNU LGPL software license.

dhex
dhex is a hex editor with a diff mode.

Emacs
Emacs is a family of text editors, characterized by their extensibility.

Frhed
Frhed is a binary file editor or hex editor for the Microsoft Windows platform.

Hex editor
A hex editor is a type of computer program that allows a user to manipulate the fundamental binary data that makes up computer files.

Hiew
Hiew (short for Hacker's view) is a popular console hex editor for Windows written by Eugene Suslikov (sen).

HxD
HxD is a hex editor and disk editor developed by Maël Hörz for Windows.

Unified Code Count (UCC)
The Unified Code Counter is a comprehensive software lines of code counter produced by the USC Center for Systems and Software Engineering.

VEDIT
Vedit is a commercial text editor for Microsoft Windows and MS-DOS from Greenview Data, Inc.

WinHex
WinHex is a hex editor useful in data recovery and forensics.