Has anyone here managed to get their custom domain (your brand) to show up in the Google OAuth login window when using Next.js and Firebase Auth? I’ve tried this on multiple projects, but Next.js doesn’t seem to have native compatibility for displaying your custom domain—instead, users still see the default ugly blahblah54321.firebaseapp.com during the Google authentication flow.
I’ve followed the usual steps: adding my custom domain in Firebase, updating the Google Cloud Console OAuth settings, and even tried hosting just the auth handler on a subdomain, but the branded domain still doesn’t appear in the OAuth prompt.
Has anyone successfully gotten around this or found a reliable workaround? Would love to hear your experience or tips!
Yes I have. Even Gemini is saying, this process is the most complex because they don’t play well.
Here’s what it said:
Reality of Firebase App Hosting
Firebase App Hosting:
Does not yet support Firebase Authentication handlers natively on custom domains.
Does not expose the “Add Integration” UI for Firebase Auth.
Requires manual setup or proxying to make /__/auth/handler work.
This is a current platform limitation, and there’s no secret config in apphosting.yaml to enable auth routing — only rewrites + an internal function reference that isn’t wired up unless the backend is pre-integrated by Firebase.
Have no fear. You may be overthinking it. Firebase Authentication with a custom domain is possible. If you want some hands-on coding assistance, feel free to drop me a direct message.