WinPcap is the Windows version of the libpcap library; it includes a driver to support capturing packets.
License: Free
Microsoft Network Monitor is a user-friendly tool with real-time monitoring and protocol analysis features, but it is limited to Windows and is not open-source. In contrast, WinPcap is an open-source library that supports multiple platforms and has strong community backing, but it lacks a user-friendly interface and real-time monitoring capabilities.