Sublime Text - Sublime Text is a sophisticated text editor for code, html and prose - any kind of text file. You'll love the slick user interface and extraordinary features. Fully customizable with macros, and syntax highlighting for most major languages.
Hex Workshop - Hex Workshop: Hex Editor, Sector Editor, Base Converter and Hex Calculator for Windows
Notepad++ - A free source code editor which supports several programming languages running under the MS Windows environment.
HextEdit - HextEdit is a proficient hex editor and disassembler for Mac.
Atom - At GitHub, we’re building the text editor we’ve always wanted: hackable to the core, but approachable on the first day without ever touching a config file. We can’t wait to see what you build with it.
BinHex CryPactor - Manipulate binary and hexadecimal strings!