How to authenticate user from different domain

Hi there, I have a platform where my users login with universal login. I also have an app that is embedded in an iframe (within Shopify). I want new users to be able to create an user account within the iframe by entering an email/password, then later after clicking a button can be redirected to my platform and already be authenticated.

My though was to use the signup API to create the new user, then fetch an access token, and use that access token to authenticate the user.

However, since I am using the @auth0/auth0-react library within my platform, I don’t believe this is possible.

How can I best accomplish my goal?

Create users via Auth0’s Management API, pass tokens from iframe to parent using window.postMessage, validate and authenticate tokens in your platform.

hi @KiteWinset , yes I am doing this. But when the parent (or my platform) receives the token in the browser, is there a way to “log them in”?