Ghidra is a software reverse engineering (SRE) framework created and maintained by the National Security Agency Research Directorate. This framework includes a suite of full-featured, high-end software analysis tools that enable users to analyze compiled code on a variety of...
OllyDbg is a 32-bit assembler level analysing debugger. Emphasis on binary code analysis makes it particularly useful in cases where source is unavailable.Discontinued
The program is no longer updated. Last version, 2.01, released in September 2013, can be still downloaded from the official website.
OllyDbg vs Immunity Debugger opinions
WinDbg is a multipurposed debugger for Microsoft Windows, distributed on the web by Microsoft as part of the Debugging Tools for Windows. It can be used to debug user mode applications, drivers, and the operating system itself in kernel mode.
EDB (Evan's Debugger) is a Qt4 based binary mode debugger with the goal of having usability on par with OllyDbg. It uses a plugin architecture, so adding new features can be done with ease. The current release is for Linux, but future releases will target more platforms.
A very powerful, versatile, and customizable Win32/Win64 user mode debugger/disassembler. PEBrowseDbg64 Interactive is not a source code debugger, but operates at the Intel x64 instruction level and therefore at the lowest level where your program executes.