Whether you’re a beginner preparing for your first mobile development job or an experienced developer brushing up, this guide features the top 50 Flutter interview questions and answers to help you ace any interview in 2025.
📌 Beginner-Level Questions
1. What is Flutter?
Answer: Flutter is an open-source UI toolkit by Google for building natively compiled applications for mobile, web, and desktop from a single codebase using the Dart programming language.
2. What is Dart?
Answer: Dart is the programming language used by Flutter. It’s optimized for UI development and provides features like ahead-of-time (AOT) compilation and a rich set of core libraries.
3. What is a Widget in Flutter?
Answer: Everything in Flutter is a widget. Widgets are building blocks of the UI—such as text, buttons, layout structures, etc.
4. Stateless vs Stateful Widget?
- StatelessWidget: Cannot change its state during the app’s lifetime.
- StatefulWidget: Can change state during the app’s lifecycle, requiring the use of
setState().
5. What is the use of pubspec.yaml?
Answer: It manages the project’s dependencies, assets, and configuration.
6. How do you run a Flutter app?
Answer: Use the command flutter run in the terminal or run from your IDE (e.g., VS Code or Android Studio).
7. What are hot reload and hot restart?
- Hot Reload: Quickly updates the UI without restarting the app.
- Hot Restart: Rebuilds the entire app state.
8. What is the difference between main() and runApp()?
main(): Entry point of the app.runApp(): Launches the widget tree from the root widget.
9. How is layout handled in Flutter?
Answer: Flutter uses a widget-based layout system. Widgets like Row, Column, Stack, and Expanded help create flexible UIs.
10. What is a BuildContext?
Answer: It’s the location of a widget in the widget tree and is used to locate other widgets, themes, or inherited widgets.
⚙️ Intermediate-Level Questions
11. What is the widget lifecycle in StatefulWidget?
createState()initState()build()didUpdateWidget()dispose()
12. What is InheritedWidget?
Answer: A special widget that allows data to be passed efficiently down the widget tree.
13. What are keys in Flutter?
Answer: Keys help Flutter distinguish between widgets when rebuilding. Useful for preserving state during reordering.
14. What is a Future in Dart?
Answer: Represents a potential value or error that will be available at some time in the future.
15. What is async/await?
Answer: Used for writing asynchronous code in a sequential way.
16. How do you handle navigation in Flutter?
Answer: With Navigator.push(), Navigator.pop(), or using named routes with MaterialApp.routes.
17. What are StatefulBuilder and setState() used for?
They allow local widget rebuilding and UI updates within StatefulWidgets.
18. How do you implement lists in Flutter?
Using ListView, ListView.builder, ListTile, or ListView.separated.
19. Difference between Expanded and Flexible?
Expanded: Fills available space.Flexible: Can use only needed space without forcing expansion.
20. How do you manage state in Flutter?
Popular methods:
setState()- Provider
- Bloc
- Riverpod
- GetX
🔌 Advanced & Real-World Questions
21. What is Flutter Engine?
Answer: It’s the core of Flutter, written in C++, that handles rendering, text layout, and Dart runtime.
22. Explain the Widget Tree vs Element Tree.
- Widget Tree: Describes UI structure.
- Element Tree: Tracks the instantiation of widgets.
- Render Tree: Represents UI layout and painting.
23. Difference between final, const, and var?
var: Mutable variable.final: Initialized once, immutable.const: Compile-time constant.
24. What is the use of Provider?
Answer: A popular state management package using inherited widgets to share data across the app.
25. What is the purpose of StreamBuilder?
Answer: It listens to asynchronous streams and rebuilds UI when new data is available.
26. How does Flutter handle animations?
With widgets like AnimatedContainer, AnimatedBuilder, and AnimationController.
27. How do you implement theme switching (dark/light)?
Using ThemeData and toggling via a state management solution or MediaQuery.
28. How to access native features in Flutter?
Using Platform Channels to communicate between Dart and native code (Java/Kotlin or Swift/Objective-C).
29. How do you reduce app size?
- Remove unused packages
- Minify assets
- Enable tree shaking
- Use
flutter build --release
30. How to test Flutter apps?
Use:
flutter_testfor unit/widget testingintegration_testfor end-to-end tests
🔍 Practical & Scenario-Based Questions
31. How do you debug Flutter apps?
With tools like Flutter DevTools, print(), debugPrint(), and breakpoints.
32. How to handle errors in Flutter?
Using try-catch, FlutterError.onError, and error boundaries.
33. What is the role of ChangeNotifier?
It’s a class that notifies listeners when a change occurs—commonly used with Provider.
34. How do you use localization in Flutter?
Using flutter_localizations and intl package with ARB files or .json.
35. What is Hot Reload vs Full Restart?
- Hot Reload: Preserves state.
- Restart: Reloads the app from scratch.
36. Can Flutter be used for web and desktop?
Yes. Flutter supports mobile, web, Windows, macOS, and Linux development.
37. What are mixins in Dart?
Code that can be reused in multiple classes using the with keyword.
38. How to persist data locally in Flutter?
Using:
- SharedPreferences
- Hive
- SQLite (sqflite)
- ObjectBox
39. What is Riverpod?
A modern, safe, and testable state management library for Flutter, which improves upon Provider.
40. When should you use CustomPainter?
When creating highly customized, complex UIs that aren’t possible with standard widgets.
🧠 Bonus: Conceptual Questions
41. What are isolates in Dart?
42. How does Flutter render widgets?
43. What are BuildContext limitations?
44. Explain the architecture of a Flutter app.
45. How do you handle deep linking?
46. What is a global key?
47. How does Flutter achieve 60fps performance?
48. How do you use FutureBuilder?
49. What’s the role of MaterialApp vs WidgetsApp?
50. How to optimize scrolling lists?
✅ Tips to Prepare for a Flutter Interview
- Practice building small apps.
- Use LeetCode or HackerRank for logic sharpening.
- Review GitHub repos and source code of popular Flutter packages.
- Stay updated with the latest Flutter versions and changelogs.
- Watch Flutter Dev YouTube tutorials.
🎯 Final Thoughts
Mastering these 50 Flutter interview questions will give you a competitive edge in your job search. Whether you’re aiming for startups or tech giants, a deep understanding of the Flutter framework, state management, and UI principles is essential.