Postman - The Collaboration Platform for API Development
strace - Trace system calls and signals. A diagnostic, debugging and instructional userspace utility.
Insomnia REST - The most intuitive cross-platform REST API Client ð´
ftrace - A function tracer for the Linux kernel.
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.
Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools.