Immunity Debugger is described as 'powerful new way to write exploits, analyze malware, and reverse engineer binary files' and is an app in the Development category. There are more than 10 alternatives to Immunity Debugger for Windows, Linux, Mac and Online / Web-based. The best alternative is x64dbg, which is both free and Open Source. Other great apps like Immunity Debugger are OllyDbg (Free), IDA (Paid), Ghidra (Free, Open Source) and WinDbg (Free).
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.