For years, the mobile development world has been defined by a single, fundamental choice: go native for performance and user experience, or go cross-platform for speed and cost-efficiency? Frameworks like React Native and Flutter have done an admirable job of bridging that gap. But what if the choice wasn't a compromise?
Enter Kotlin Multiplatform (KMP), a technology from JetBrains that is rapidly maturing and changing the way we think about app development. It doesn't ask you to choose between native and cross-platform; it offers a third, more nuanced path.
This guide will break down what KMP is, how it differs from its competitors, and help you decide if it's the right choice for your next project in 2025.
What is Kotlin Multiplatform, Exactly?
Unlike frameworks that aim for a "write once, run anywhere" UI, Kotlin Multiplatform takes a different approach. KMP allows you to share business logic, not UI.
This is the key distinction. You write your core application logic—things like networking, data storage, analytics, and business rules—in a shared Kotlin module. This shared code is then compiled into a native library for each target platform (an AAR for Android, a framework for iOS). Your UI, however, remains fully native.
- On Android, you build your UI with Jetpack Compose.
- On iOS, you build your UI with SwiftUI.
You get the efficiency of shared logic without ever compromising on the native performance, look, and feel that users expect.
KMP vs. React Native & Flutter: The Showdown
How does KMP stack up against the established players?
1. User Interface (UI) and User Experience (UX)
- KMP: The undisputed winner. Since the UI is 100% native (Jetpack Compose and SwiftUI), your app has direct access to all platform-specific APIs, animations, and conventions from day one. There is no "bridge" and no performance penalty. The user experience is identical to a traditionally built native app.
- React Native/Flutter: These frameworks do an excellent job of mimicking native components, but they are ultimately drawing their own UI. This can sometimes lead to subtle performance issues, a slight delay in adopting new OS features, and a feeling that the app is not "quite" native.
2. Performance
- KMP: Again, KMP has the edge. The shared Kotlin logic compiles down to the native format for each platform (JVM bytecode for Android, native binaries for iOS). There is no JavaScript bridge or rendering engine overhead.
- React Native/Flutter: While modern devices have made them incredibly fast, they still have an abstraction layer that can, in performance-intensive applications, be a bottleneck compared to pure native code.
3. Code Sharing & Efficiency
- KMP: Allows you to share anywhere from 30% to 70% of your codebase. You share the complex, non-visual parts of your app, which are often the most difficult to get right and test.
- React Native/Flutter: Offer the potential for 90%+ code sharing, which can lead to faster initial development for simpler apps. The trade-off is the compromise on native UX and performance.
When Should You Choose Kotlin Multiplatform?
KMP is not a silver bullet, but it is a powerful strategic choice for specific types of projects. Consider KMP if:
- A Flawless Native UX is Non-Negotiable: If your app relies heavily on complex animations, platform-specific features (like Widgets or Live Activities), or simply must feel perfectly at home on both Android and iOS, KMP is the ideal choice.
- Your App Has Complex Business Logic: The more complex your backend interactions, data models, and business rules, the more value you get from sharing that logic in a single, type-safe codebase.
- Long-Term Maintainability is Key: By separating logic from UI, you create a more robust and maintainable architecture. A change in business rules only needs to be made once. This is a core principle we follow when designing resilient mobile architectures.
Conclusion: The Best of Both Worlds
Kotlin Multiplatform represents the maturation of the app development ecosystem. It acknowledges that the best user experience is native, while the most efficient development process involves sharing code. By allowing developers to share the logic and build the UI natively, KMP offers a powerful synthesis that was previously out of reach.
It may not be the fastest choice for a simple proof-of-concept, but for serious, long-term applications where quality and performance are paramount, Kotlin Multiplatform is no longer just hype—it's the future. At Norseson Labs, we're excited to leverage its power to build the next generation of high-performance mobile applications.
