How to get base url for user

I’m building out an integration for users to share tasks from our app to their own Jira installations. I’ve got the Oauth flow working, but I’m not sure how to get a specific user’s base url for the Jira install they’ve authenticated for. Is there some documentation around this that I’m missing?

I’m writing my end of things in Node if that helps, thanks!

Apparently there were some bits of documentation I did not see initially. I found the ‘’ endpoint which tells me what I need to know.