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.
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
tcpdump - tcpdump is a common packet analyzer that runs under the command line.
tcpflow - tcpflow, a TCP Flow Recorder, is a program that captures data transmitted as part of TCP...
Postman - The Collaboration Platform for API Development
Ethereal - Ethereal® is used by network professionals around the world for troubleshooting, analysis...