HxD - HxD is a carefully designed and fast hex editor which, additionally to raw disk editing and...
OllyDbg - OllyDbg is a 32-bit assembler level analysing debugger.
Hex Workshop - Hex Workshop: Hex Editor, Sector Editor, Base Converter and Hex Calculator for Windows
X64dbg - X64dbg is a debugging software that can debug x64 and x32 applications.
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.
Hex Fiend - A fast and clever open source HEX editor for Mac OS X.