</>Software engineering

Mobile App Developer

Practice Android, iOS, Flutter and React Native questions from Mobile App Developer interviews: lifecycle, state, offline, performance and releases.

Questions: 100
Interview Qs: 30
Judged problems: 93
Skills: 9

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About the role

A Mobile App Developer builds apps that people install on Android phones and iPhones. On a normal day you build screens from designs, connect them to backend APIs, handle login and push notifications, and fix crashes reported from real devices. You may work natively with Kotlin and Jetpack Compose on Android or Swift and SwiftUI on iOS, or use a cross-platform framework like Flutter or React Native to ship to both from one codebase.

Mobile has its own challenges. Phones have limited battery, memory and often slow or no network, the operating system can kill your app at any time, and there are thousands of screen sizes and OS versions. A good mobile developer handles the app lifecycle correctly, saves state, works offline, keeps the UI smooth at 60 to 120 frames per second, and respects user privacy and permissions.

As you grow, you own the app architecture, set up CI/CD for builds and store releases, monitor crash and performance data, manage staged rollouts, and work with product and backend teams on API design and feature flags.

Practise by level

easy

Easy challenges

34 questions

medium

Medium challenges

34 questions

hard

Hard challenges

32 questions

Open the full question bank (100 questions) →

Mock interview

easy

Screening round

4 questions · 4 min each · pass 50%

medium

Technical round

5 questions · 4 min each · pass 60%

hard

Final round

6 questions · 3 min each · pass 70%

Coding problems for mobile app developers

All 93 problems →

Skills in this track

Learning roadmap

1
Programming language basics
Pick a platform and learn its language well: Kotlin for Android, Swift for iOS, or Dart or TypeScript for cross-platform. Focus on null safety, collections, classes and async code.
2
UI and navigation
Build screens with Jetpack Compose, SwiftUI, Flutter widgets or React Native components. Learn layouts, lists, navigation, theming and handling different screen sizes.
3
Lifecycle, state and architecture
Understand the app and screen lifecycle, configuration changes and process death. Learn MVVM or a similar pattern with ViewModels, unidirectional data flow and dependency injection.
4
Data, networking and offline
Call REST or GraphQL APIs, parse JSON, handle errors and retries, and store data locally with Room, SwiftData, Core Data or SQLite. Build an offline-first screen that syncs later.
5
Testing, performance and security
Write unit and UI tests, profile with Android Studio Profiler or Xcode Instruments, fix jank and memory leaks, and store secrets in Keystore or Keychain.
6
Publishing and portfolio
Publish at least one app to the Play Store or App Store. Learn signing, versioning, store listings, staged rollouts and crash reporting with tools like Firebase Crashlytics.