Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
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.
Weer - A HTTP protocol debugger with Chrome DevTools frontend interface
Postman - The Collaboration Platform for API Development
Cellist - Cellist is an all-in-one HTTP debugging proxy software designed for OS that provides a straightforward approach to put a proxy between the HTTP client and the internet.