Yes you can use! You only have to change the rules from your database. It must be read and write == null. Everything will work just fine!

No you can't use it without auth. If you don't login user via email. You make a http server and generate JWT (Json web token ) then use this JWT accordingly.

With firebase, you could either use your own custom authentication logic or let the users use an anonymous authentication strategy with a possibility of later elevating the profile to an authenticated user.

But if you do not wish to associate any kind of authentication with the users, you could use deepstream. It is completely open sourced and provides a no auth mechanism where any user who connects to your app can start using it without any authentication step.

You can somehow use the firebase anonymous authentication if you do not want to really do any authentication.

NB: You can not interact with the firebase realtime database and all other service without any form of authentication.

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