Saving user data in backend

Hi can I somehow save user identifier in database to be able to retrieve data anytime.
And is there any unique identifier for user that is not changing


But you’ve posted under extension ideas.

And your question doesn’t make 100% sense

What are you trying to do?

I need to save data for broadcaster in backend. I need to know broadcaster user id to know that configuration belongs to that user

In the backend of what? I assume you mean a Twitch Extension, but you have not said

You can Parse the passed JWT to collect the broadcaster/channel/user_id