Winsock Packet Editor - WPE Pro is a packet editor.
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.
Scapy - Scapy is a powerful interactive packet manipulation program.
Debookee - Debookee is the simplest & most powerful network traffic analyzer for macOS.
Nipper - Nipper - Neat Internet Protocol Packet EditoR - is a graphical packet generation tool.
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.