Packet Sender - Packet Sender can send and receive UDP, TCP, and SSL on the ports of your choosing.
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
PortMapper - Do you need to map a specific TCP or UDP port on your machine to another port on another machine?
Proxyman.io - Proxyman is a high-performance macOS app, which enables developers to view HTTP/HTTPS requests from apps and domains.
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
Postman - The Collaboration Platform for API Development