Libpcap, WinPcap, and Npcap provide the packet-capture and filtering engines of many open-source and commercial network tools, including protocol analyzers ( packet sniffers), network monitors, network intrusion detection systems, traffic-generators and network-testers. C++ programs may link directly to the C API or use an object-oriented wrapper.

NET languages, and scripting languages generally use a wrapper no such wrappers are provided by libpcap or WinPcap itself. The pcap API is written in C, so other languages such as Java. Monitoring software may use libpcap, WinPcap, or Npcap to capture network packets traveling over a computer network and, in newer versions, to transmit packets on a network at the link layer, and to get a list of network interfaces for possible use with libpcap, WinPcap, or Npcap.

Unix-like systems implement pcap in the libpcap library for Windows, there is a port of libpcap named WinPcap that is no longer supported or developed, and a port named Npcap for Windows 7 and later that is still supported. While the name is an abbreviation of packet capture, that is not the API's proper name. In the field of computer network administration, pcap is an application programming interface (API) for capturing network traffic.

Example pcap files