Firebase Integration Flutter Interview Questions
7 questions
How do you implement Firebase Authentication in Flutter?
Add the `firebase_auth` package, initialize Firebase in `main()`, then use `FirebaseAuth.instance` to sign users in (email/password, Google, etc.) and listen to `authStateChanges()` to react to login/logout across the app.
What's the difference between Firestore and the Realtime Database?
Firestore is a newer, document/collection-based database with richer querying, automatic multi-region scaling, and better offline support; the Realtime Database is a simpler single JSON tree, cheaper for very high-frequency small writes but with weaker querying.
How do push notifications work with Firebase Cloud Messaging in Flutter?
The app registers with FCM to get a unique device token, your backend (or Firebase console) sends a message to that token via the FCM API, and the `firebase_messaging` package delivers it to the app in foreground, background, or terminated states via different handlers.
What is Firebase Remote Config used for?
Remote Config lets you change app behavior and appearance — feature flags, A/B test variants, default values — without shipping a new app release, by fetching key/value parameters from the Firebase backend at runtime.
How do Firestore Security Rules work?
Security Rules are a separate, declarative configuration that Firestore evaluates server-side on every read/write request, deciding whether to allow it based on the requesting user's auth state and the data being accessed — they're your only real line of defense since client-side checks can be bypassed.
How do you set up Firebase Crashlytics to catch Flutter errors?
Wire both FlutterError.onError (for framework/widget-build errors) and PlatformDispatcher.instance.onError (for uncaught async errors) to record errors to Crashlytics, since neither alone catches every category of error.
How do Firebase Remote Config and A/B Testing work together?
Remote Config supplies the actual parameter values your app reads at runtime; Firebase A/B Testing sits on top of it, automatically assigning users to different Remote Config parameter variants and measuring which performs better against a chosen metric.