What data am I sending wrong in this request to broadcast a message?

As you’re using onAuthorized , it looks like you’re attempting to do this on the client side? You can’t create tokens client side as that would mean exposing your secret which would be a huge security breach.

Yes, I am. Thank you very much.

You should only be creating tokens on your EBS, and the user_id in the JWT isn’t “the userId from before”, it’s the id of the extension owner.

I am the extension owner, shouldn’t the id from before be the same one, in this case in particular at least?
Even if It wouldn’t work for other cases

Edit: Does the API know the message coming from the front end?