Really Simple Test Tool. Acts as a TCP/IP or UDP listener and binds on a TCP or UDP socket. When a TCP/IP client connects to this Server, input from the client is displayed in a list (IP-Address / Text). Messages must always be terminated with a Newline character. In a text field of the server window, you can edit (or copy-paste) some response text and send it back to the client. The entire conversation is visible in a Dialog History List. Only one single client is able to connect to this server simultaneously (it is just a test tool, not a chat server!). See window layout draft attached. It is easy with C#, i know.