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
Microsoft Research Detours - Detours is a software package for re-routing Win32 APIs underneath applications.
EasyHook - The reinvention of Windows API Hooking
Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools.
madCodeHook - "madCodeHook" offers everything you need to hook code (mostly APIs).
Postman - The Collaboration Platform for API Development