I'm sorry if it's a duplicate question, but I haven't found any answers that answer my question.
I use firebaseConfig to initialize firebase in my app. As far as I know, there's no way to secure keys when using only client-side code so anyone may access my firebase config.
I've read about security rules. But what prevents bad guys from siging up in my app, copying my config, and starting local server, logining in and accessing database data?
I thought about authDomain, but it allows using localhost, even if I can prevent from sending requests from localhost, the app needs maintaining so it's required to use localhost from time to time.
So the questions is how to prevent from signin-up, and using firebase key on localhost.
By the way, is it secure enough to use stripe API payments without in my single page app?