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.

Debookee - Debookee is the simplest & most powerful network traffic analyzer for macOS.

PCAPdroid - PCAPdroid is an android app to capture the phone traffic and analyze it remotely (e.g. via Wireshark). The traffic can be easily downloaded from a remote device thanks to the integrated HTTP server, or streamed to a remote UDP receiver.

Packetyzer - Packetyzer provides a Windows user interface for the Ethereal packet capture and dissection library.

Ettercap - Ettercap is a suite for man in the middle attacks on LAN.

PacketSled - PacketSled is next generation network forensics and breach detection.