Hi Eldersamuel,

You do can use Apple authentication without using Firebase but keep in mind that Apple will call the provided Return URL upon user authentication events, so you will need to implement an endpoint to handle that calls.

I can’t tell you how to implement such endpoint or whether skipping its implementation will result in critical errors as Firebase manages that part of the integration for me. What I do can tell you however is the server URL you provide when configuring Sign in with Apple must be a reachable URL (e.g. https://your-domain.com/api/auth/apple), and http://localhost it’s definitely not.

Cheers