Q:

Firebase Multiple Accounts are signed at the same time

I want my users to sign in with multiple accounts (Not linking multiple providers)
like gmail, it allows you to use multiple signed in accounts at the same time
you can check all inboxes for all accounts at the same time
e.g. I am a User and I want to use two accounts
john@example.com & john21@example.com
I want both emails signed in (there are two auth tokens in this case)
I have searched about it in Firebase docs, I couldn't find anything
Is this possible in Firebase Auth?

A:

From one project, no i don't think you can have two users signed in.
You can create another Firebase project and add your app there (you'll be able to add your sha-1 on either one). You can then look up their approach to using two Firebase projects in one app.
You'll be able to sign in with two users in this way if there are two projects to sign in with. You'll have to manage your users across both the databases on your own i.e same user will have to have an account with same credentials made in both the projects.
It's complicated but it can be done. I use anonymous sign in from two separate projects simultaneously in my app, both users are the same... Just their projects are different.

