Charles - HTTP proxy / HTTP monitor / Reverse Proxy
Cppcheck - Cppcheck is an analysis tool for C/C++ code. It detects the types of bugs that the compilers normally fail to detect. The goal is no false positives. CppCheckDownload cppcheck for free.
Postman - The Collaboration Platform for API Development
Coverity Scan - Find and fix defects in your Java, C/C++ or C# open source project for free
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Clang Static Analyzer - The Clang Static Analyzer is a source code analysis tool that finds bugs in C, C++, and Objective-C...