Kotlin Multiplatform vs Flutter

Kotlin Multiplatform (KMP) and Flutter take opposite approaches to cross-platform development. KMP shares business logic while keeping native UI on each platform. Flutter shares everything — UI, logic, and rendering — using a custom engine.

Shared Logic vs Shared Everything

KMP lets you write shared Kotlin modules for networking, data serialization, business rules, and local storage. Each platform then uses its own native UI framework (SwiftUI on iOS, Jetpack Compose on Android). The result is apps that are indistinguishable from fully native apps.

Flutter provides a single Dart codebase that renders identically on all platforms using the Skia engine. You write the UI once, and it looks the same everywhere. This maximizes code sharing (90%+) but means your iOS app does not automatically match iOS design conventions.

Team Structure Implications

KMP requires developers who can build native UI on each platform. You need iOS expertise (SwiftUI) and Android expertise (Compose), plus shared Kotlin logic developers. This is more expensive but produces the highest-quality native experience.

Flutter requires a single team that knows Dart and Flutter. One developer can build for both platforms, significantly reducing team size and communication overhead.

System Design Considerations

For system design interviews, the mobile framework choice affects client architecture but not backend design. Focus on API design, data synchronization, offline support, and push notifications. The shared vs native UI question is a client-side implementation detail.

See our comparison guides and interview questions.