You can use HexChat on Windows, Mac, and Linux. You can use Textual on MacOS, which is nicer, but needs to be compiled from its source code to be used for free. Alternately, you can use the web client on any device, including mobile devices.
MAKE SURE TO USE SSL/TLS
Traditional connection string: chat.termer.net +6697
Traditional connection string: ajx5lra4rvacgcrlsaqkh3eh57u6oi6dhbg3jvww5yphrxa4doq5jxid.onion 6667