HxD - HxD is a carefully designed and fast hex editor which, additionally to raw disk editing and...

Notepad++ - A free source code editor which supports several programming languages running under the MS Windows environment.

IDA - The best-of-breed binary code analysis tool, an indispensable item in the toolbox of world-class software analysts, reverse engineers, malware analyst and cybersecurity professionals.

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

Notepadqq - Notepadqq is a linux clone (identical application) of Notepad++