The old command-line method required opening separate terminals for listening vs. connecting. Netcat Gui 1.2 simplifies this with a simple radio button at the top of the window. Select to act as a server or "Connect Mode" to act as a client. The available input fields change dynamically based on your selection.
How to Use Netcat Commands: Examples and Cheat Sheets - Varonis Netcat Gui 1.2