ftrace - A function tracer for the Linux kernel.
OllyDbg - OllyDbg is a 32-bit assembler level analysing debugger.
Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools.
X64dbg - X64dbg is a debugging software that can debug x64 and x32 applications.
API Monitor - API Monitor is a software that monitors and displays API calls made by applications and services. Its a powerful tool for seeing how Windows and other applications work or tracking down problems that you have in your own applications
Nirsoft Simple Program Debugger - Nirsoft Simple Program Debugger is a debugging software that analyzes and displays all major debugging events across your computer, after connecting to either the running program or starting a new program in the debugging mode.