Kotlin Multi-platform vs Cross-platform for Mobile Apps in 2025

1. What is Kotlin Multi-platform?

2. What is Cross-platform Development?

3. Key Differences Between Kotlin Multi-platform and Cross-platform

4. Pros and Cons of Kotlin Multi-platform

5. Pros and Cons of Cross-platform Frameworks

6. Code Comparison: KMP vs. Flutter

7. When to Choose Kotlin Multi-platform?

8. When to Choose Cross-platform Frameworks?

9. App Use Cases

10. Apps That Use Kotlin Multi-platform

11. Conclusion

12. 10 FAQs About Kotlin Multi-platform vs Cross-platform

What is Kotlin Multi-platform?

Kotlin Multi-platform (KMP or KMM) is a framework developed by JetBrains that enables you to share business logic and core functionalities across multiple platforms, such as iOS, Android, web, and desktop. Unlike traditional cross-platform solutions, KMP allows developers to write platform-specific code alongside shared code for a seamless native experience.

Key Features:

• Write shared code for business logic while using platform-specific UI.

• Interoperable with native languages (Swift for iOS, Java/Kotlin for Android).

• Uses Gradle for dependency management.

• Backed by Kotlin’s robust ecosystem and JetBrains’ continuous support.

Example: Shared Code in Kotlin Multi-platform

// commonMain/src/CommonCode.kt
expect fun platformName(): String
fun greet(): String {
    return "Hello from ${platformName()}"
}
// androidMain/src/Platform.kt
actual fun platformName(): String {
    return "Android"
}
// iosMain/src/Platform.kt
actual fun platformName(): String {
    return "iOS"
}

In this example, the greet function is shared across platforms, while the implementation of platformName is platform-specific.

What is Cross-platform Development?

Cross-platform development refers to building apps that can run on multiple platforms using a single codebase. Frameworks like Flutter, React Native, and Xamarin use this approach, often relying on a custom rendering engine or a bridge to communicate with native APIs.

Key Features:

• Single codebase for multiple platforms.

• Access to native functionalities through bridges or plugins.

• Faster development and reduced cost compared to separate native apps.

• Supported by large communities and enterprises.

Example: Flutter Cross-platform Code

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("Cross-platform Example")),
        body: Center(
          child: Text("Hello from Flutter!"),
        ),
      ),
    );
  }
}

This Flutter code runs on both iOS and Android without requiring separate platform-specific implementations.

Key Differences Kotlin Multi-platform and Cross-platform

Pros and Cons of Kotlin Multi-platform

Pros:

• Native performance.

• Maximum flexibility for platform-specific features.

• Strong tooling with IntelliJ IDEA and Android Studio.

• Easier adoption for teams already using Kotlin.

Cons:

• Steeper learning curve for teams unfamiliar with Kotlin.

• Requires writing separate UI code for each platform.

• Relatively new, with a smaller community compared to other frameworks.

Pros and Cons of Cross-platform Frameworks

Pros:

• Single codebase reduces development time and cost.

• Large ecosystem of plugins and libraries.

• Ideal for building MVPs or simple apps.

• Supported by giants like Google (Flutter) and Facebook (React Native).

Cons:

• Potential performance issues with complex animations or large apps.

• Custom UI rendering can lead to non-native look and feel.

• Dependence on third-party libraries for accessing native APIs.

Code Comparison: KMM vs. Flutter

Kotlin Multi-platform Example: Network Call

// Shared Code
expect class HttpClient()
fun fetchData(url: String): String {
    val client = HttpClient()
    return client.get(url)
}
// Android Implementation
actual class HttpClient {
    fun get(url: String): String {
        // Use Android's networking APIs
        return "Android Response"
    }
}
// iOS Implementation
actual class HttpClient {
    fun get(url: String): String {
        // Use iOS networking APIs
        return "iOS Response"
    }
}

Flutter Example: Network Call

import 'package:http/http.dart' as http;
Future<String> fetchData(String url) async {
  final response = await http.get(Uri.parse(url));
  if (response.statusCode == 200) {
    return response.body;
  } else {
    throw Exception("Failed to fetch data");
  }
}

When to Choose Kotlin Multi-platform?

Kotlin Multi-platform is ideal if:

• Your team has Kotlin expertise.

• Your app has complex logic or requires platform-specific optimizations.

• You want to share code across mobile, web, and desktop platforms.

When to Choose Cross-platform Frameworks?

Cross-platform frameworks like Flutter and React Native are ideal if:

• You want to reduce time-to-market.

• Your app has a relatively simple architecture.

• You don’t require high-performance native features.

• Your team is proficient in Dart or JavaScript.

App Use Cases for KMM

Kotlin Multiplatform (KMM) is a powerful tool for sharing code across multiple platforms, making app development more efficient. Here are some key use cases for Kotlin Multiplatform within an app:

1. Shared Business Logic

• Centralize and share the app’s core functionality across platforms (iOS, Android, desktop, web).

• Data validation logic (e.g., form validation rules).

• Algorithms (e.g., search, sorting, recommendations).

• Business rules (e.g., pricing calculations, discounts).

2. Networking and API Clients

• Implement network requests, REST/GraphQL API calls, and WebSocket communications in a single codebase.

• Share HTTP clients (e.g., with Ktor) and manage serialization (e.g., with Kotlinx.serialization).

3. Data Layer (Repositories & Persistence)

• Share code for database access, repositories, and data syncing.

• Use libraries like SQLDelight for shared database interactions across iOS and Android.

4. Authentication and Security

• Unified logic for authentication workflows (e.g., login, signup, session management).

• Shared encryption logic for storing sensitive data.

5. Cross-Platform Algorithms

• Implement platform-agnostic algorithms (e.g., image processing, machine learning preprocessing, or custom data manipulation).

6. State Management

• Create shared state management logic (e.g., Redux-style stores or MVVM models) for consistent app behavior across platforms.

7. Multiplatform Analytics

• Share analytics logic to track user behavior and events consistently.

• Event logging and analytics tagging.

• Error reporting and crash monitoring.

8. Custom Middleware and Utilities

• Centralize helper utilities such as string manipulation, date/time utilities, or math functions.

• Share middleware components for logging, debugging, or event tracking.

9. Real-Time Communication

• Unified logic for real-time features like chat or collaborative editing (e.g., using WebSockets).

10. Localization and Internationalization

• Share logic for handling translations, currency formatting, and other locale-specific features.

11. Cross-Platform Libraries/Plugins

• Develop your own reusable libraries for cross-platform use within the app.

• Useful for SDKs, app integrations, or internal toolkits.

Apps That Use Kotlin Multi-platform

Several high-profile apps and companies have successfully integrated Kotlin Multi-platform into their development pipelines. Here are some noteworthy examples:

1. Cash App by Square

Cash App uses KMP to share business logic between Android and iOS. This has enabled Square to maintain a consistent codebase for critical functionalities such as payment processing and account management.

2. Netflix Studio

Netflix leverages KMP in its Studio application, which supports content creators and editors by sharing core logic across platforms.

3. Philips Hue

The Philips Hue team uses KMP to manage shared features like device connectivity and data synchronization for its smart lighting apps.

4. Vimeo

Vimeo implemented KMP for portions of their app to streamline shared features such as video uploading and processing.

5. PlanGrid by Autodesk

PlanGrid uses KMP to ensure reliable cross-platform functionality for construction and project management tools.

Conclusion

Both Kotlin Multi-platform and Cross-platform frameworks offer unique benefits for mobile app development. While KMP excels in flexibility and native performance, cross-platform frameworks shine in development speed and simplicity. Your choice depends on the project’s requirements, your team’s expertise, and your long-term goals. For more information, explore -

• Kotlin Multi-platform Documentation

• JetBrains KMP Resources

• Netflix Tech Blog on KMP