netcat - Netcat is a featured networking utility which reads and writes data across network connections...
WinPcap - Industry-standard tool for link-layer network access in Windows.
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.
Npcap - Npcap is the Nmap Project's packet sniffing library for Windows.
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
Proximac - An open-source command-line program for Mac OS X to make any app work through a proxy server.