DiamondCS OpenPorts is a CLI (command line interface/console) tool that allows you to see all open TCP and UDP ports on your system, including the owner process. OpenPorts includes 5 different display styles to not only improve human reading of the display on the command line, but also to help people who write scripts.

OpenPorts combines all the features of the other command-line port to process mappers, like FPort and Netstat whilst adding even more features. Best of all, OpenPorts is free for personal use.