Kotlin Multiplatform Mobile: Is It Ready to Replace Flutter and React Native?

A Different Approach to Cross-Platform

Unlike Flutter and React Native, which render their own UI on top of native platforms, Kotlin Multiplatform (KMP) shares business logic — networking, data models, view models — while letting each platform keep its fully native UI (SwiftUI on iOS, Jetpack Compose on Android).

Sharing a Data Layer

// commonMain - shared across iOS and Android
class ProductRepository(private val api: ApiClient) {
    suspend fun getProducts(): List<Product> {
        return api.get("/products").body()
    }
}

@Serializable
data class Product(val id: String, val name: String, val price: Double)

Platform-Specific UI, Shared ViewModel

// commonMain
class ProductListViewModel(private val repository: ProductRepository) {
    private val _state = MutableStateFlow<List<Product>>(emptyList())
    val state: StateFlow<List<Product>> = _state

    suspend fun load() {
        _state.value = repository.getProducts()
    }
}

// androidMain - Jetpack Compose UI
@Composable
fun ProductListScreen(viewModel: ProductListViewModel) {
    val products by viewModel.state.collectAsState()
    LazyColumn {
        items(products) { product => Text(product.name) }
    }
}

// iosMain - SwiftUI consuming the same shared ViewModel
struct ProductListView: View {
    @StateObject var viewModel: ProductListViewModelWrapper

    var body: some View {
        List(viewModel.products, id: \.id) { product in
            Text(product.name)
        }
    }
}

The Core Trade-off vs Flutter/React Native

When KMP Makes Sense

• You need pixel-perfect native UI conventions on each platform (not “close to native” — actually native)
• You already have native iOS/Android teams and want to reduce duplicated business logic, not UI code
• Deep platform-specific integrations are a priority and you don’t want an abstraction layer in the way

When KMP Is the Wrong Choice

• You want a single team building one UI codebase for both platforms — that’s Flutter or React Native’s actual value proposition
• You don’t have (or want to build) separate iOS and Android UI expertise
• Fast prototyping matters more than long-term native UI fidelity

Current Maturity

KMP for mobile (KMM) is production-ready and used by major companies, but the ecosystem of shared libraries is smaller than Flutter’s or React Native’s, and you’re still writing and maintaining two UI codebases — just with shared business logic underneath.

Conclusion

KMP isn’t a drop-in replacement for Flutter or React Native — it’s a different trade-off entirely, sharing logic while keeping UI fully native and platform-specific. Choose it when native UI fidelity matters more than single-codebase UI development speed.