madCodeHook - "madCodeHook" offers everything you need to hook code (mostly APIs).
Postman - The Collaboration Platform for API Development
Deviare API Hook - Deviare is a professional open source hooking engine for instrumenting arbitrary Win32 functions, COM objects, and functions which symbols are located in program databases (PDBs).
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Microsoft Research Detours - Detours is a software package for re-routing Win32 APIs underneath applications.
soapUI - SoapUI Pro is one of the most prominent API testing platforms around, allowing developers to quickly prototype the functions of their apps and get them to market with little hassle.