010 Editor - 010 Editor: Professional hex editor with Binary Templates. A fast, flexible, easy-to-use hex editor.
HxD - HxD is a carefully designed and fast hex editor which, additionally to raw disk editing and...
iBored - iBored is not a pure hex editor but rather a disk block editor, which also can be used to edit files in hex.
Hex Workshop - Hex Workshop: Hex Editor, Sector Editor, Base Converter and Hex Calculator for Windows
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.
Kaitai Struct - Kaitai Struct is a formal language for binary format specification that can be compiled into parser code