is this possible

[KingTheGuy]

[question] is it possible to use the websocket to connect to external servers?

[Tsubashi]

I am not sure what you mean by your question. The README does have some verbiage regarding connecting to third party servers.

In order to be able to execute the /connect and /wsserver commands, cheats must be enabled. This means that connecting on third party servers is not possible, and only on the dedicated server when cheats are enabled. It is possible to connect on a singleplayer world and join a server after that, but commands executed by the websocket server will not work. Events will still be sent by the client however.

Does that answer your question?

[Sandertv]

I am not sure if you're able to use the websocket server to connect to external servers. In case you're using a platform that does not have access to the /transferserver command, it's rather unlikely that the websocket server will be able to call it. I haven't personally tried though, and I do know the websocket server has access to some commands that a player cannot access, so it is worth a try.