Pros and Cons of Developing an App in Kotlin Multiplatform

Updated Nov 11, 2024 • 11 min read

After the recent success of mobile frameworks like Flutter and React Native, a new contender for multi-platform development is slowly getting more and more popular. Kotlin Multiplatform technology promises to harness the power of shared code for multiple platforms like Flutter and React Native while still having the possibility of platform-specific code for more advanced features.

Even though this sounds very promising, like all things, it has its advantages and drawbacks. Let us analyze them in this article.

Introduction to Kotlin Multiplatform

Kotlin Multiplatform is a cutting-edge technology developed by JetBrains that empowers developers to share Kotlin code across different platforms, including Android, iOS, macOS, Windows, Linux, and the web. This innovative approach allows developers to write platform-specific code for native UI implementation and platform API interactions while sharing business logic between platforms. By leveraging Kotlin Multiplatform, developers can create cross-platform applications with a shared codebase, significantly reducing development time and effort. This technology is a key feature of the Kotlin programming language, making it an attractive option for developers looking to streamline their workflow and deliver high-quality applications across multiple platforms.

Pros of Developing an App in Kotlin Multiplatform

Developing an app in Kotlin Multiplatform offers several compelling advantages:

Code sharing: One of the most significant benefits is the ability to share Kotlin code across different platforms. This not only reduces development time but also increases code reuse, making the development process more efficient.
Native performance: Kotlin Multiplatform allows developers to use platform-specific APIs and native code, ensuring that each platform achieves native performance. This means your app will run smoothly and efficiently on all supported platforms.
Cross-platform compatibility: With Kotlin Multiplatform, you can create applications that run seamlessly on multiple platforms, including Android, iOS, macOS, Windows, Linux, and the web. This broad compatibility ensures that your app reaches a wider audience.
Easy maintenance: Maintaining a single codebase for multiple platforms simplifies the maintenance process, reducing costs and increasing efficiency. Developers can easily update and manage the app without having to make changes across multiple codebases.
Faster development: By sharing code and using platform-specific APIs, developers can speed up the development process. This allows for quicker iterations and faster time-to-market for your applications.

The greatest thing about KMP is something that it shares with the aforementioned frameworks – it allows you to write the same code once and have it working on multiple device types. But KMP does so in a very distinct way:

It’s easily expendable. To achieve certain behaviors on both Flutter and React Native platforms, you mostly use the API prepared by the framework creators. Adding platform-specific code can be difficult and error-prone. But in Kotlin Multiplatform, you can create your own common API for some platform-specific functionalities with ease. For example, for drawing graphics, Android uses its native Canvas whereas desktop uses the Skia rendering engine. If there is a need, you can craft a common API that will draw the same things for the user, but underneath will use the technology appropriate for the platform in question.
You can scale an existing application with KMP. For example, if an Android and an iOS application already exist, and a certain new functionality needs to be added for both, this can be done in Kotlin Multiplatform to reduce the development time needed for implementation.

Write platform specific code

In KMP, you have a lot of freedom when it comes to using platform-specific code. You can write an Android UI in Jetpack Compose, an iOS UI in SwiftUI, and make them both use a common codebase for business logic.

But you could also use a KMP library like Compose Multiplatform to share both UI and business logic code. Even with such an approach, if you find that two platforms require very different approaches for a feature, Kotlin Multiplatform provides you with an easy way to tackle them independently and add platform specific implementations to your common codebase for future use.

Kotlin language

When working in KMP, Android and some backend developers will feel right at home since the code is all written in the Kotlin language. The Android Gradle Plugin ensures compatibility with Kotlin Multiplatform projects in Android Studio. According to the Stack Overflow Survey 2022, Kotlin is more popular (9.16% vs 6.54%) and more loved than Dart – the language of Flutter.

Kotlin also offers more compile-time safety than JavaScript – the language of React Native, which means that the developers get notified if something is wrong as soon as they compile the app rather than after it has been run. Thanks to that, developers can find bugs early and it improves their productivity. Also, since Kotlin is very well regarded in the programming community, a lot of people are willing to work with it.

Cons of developing an app in Kotlin Multiplatform

Beta version

At the time of writing this article, Kotlin Multiplatform is in its beta phase. According to JetBrains - the company behind the Kotlin language, it should be safe to use in your projects already. Despite that, it’s important to keep in mind that this technology is still not fully matured. Some changes to the API are possible, but there is a great focus on minimizing potential migration issues.

Kotlin Multiplatform is still in its beginning phase, so there are noticeably less resources online to learn from. Sometimes it might take a developer a lot of time to find a solution to their problem, as they could be one of the first people to encounter it.

Kotlin Multiplatform facilitates the development of cross platform projects by allowing code sharing among various platforms, thus alleviating the burden of writing and maintaining separate codebases for each platform while still offering native programming advantages.

Despite that fact, JetBrains regularly puts out detailed documentation on their official website, where it’s possible to find answers to the most important questions and better understand how KMP works.

Years of trial and error on different platforms have led to an established way to write clean architecture. With Kotlin Multiplatform, code architecture is still being explored in different ways, and only with time will the best approach be discovered.

You can of course achieve clean code in KMP, but there are no mainstream well-tested architectural guidelines, so an experienced developer is often needed to establish them by oneself.

Swift limitations and code magic

When using KMP for an iOS app, at the time of writing this article, there are still some limitations and unexpected behaviors when Kotlin code is translated to Objective-C (the language of iOS). For example, default method parameters in Kotlin don’t work after being translated, as Objective-C doesn’t support default parameters at all. JetBrains are currently working to resolve this problem.

Kotlin Multiplatform enables developers to leverage the advantages of native programming while simplifying code maintenance and sharing across different platforms.

The translation process from Kotlin to Objective-C at the moment is a bit time-consuming, which might slow down the iOS part of development. Also, you can sometimes expect underscore characters to be added to your translated Objective-C code. This is one of the most odd bugs – it will not break your application, but may cost you several hours of wondering what and why is happening to your mobile application.

Thankfully, these issues are not something stopping you from creating a fully functional multiplatform application, but rather they are small annoyances that should be fixed or improved with time by the JetBrains team.

Comparison to Other Cross-Platform Frameworks

Kotlin Multiplatform is often compared to other cross-platform frameworks such as Flutter, React Native, and Xamarin. While these frameworks offer similar benefits, Kotlin Multiplatform stands out with several unique advantages:

Native performance: Unlike some other frameworks, Kotlin Multiplatform allows developers to use platform-specific APIs and native code, achieving native performance on each platform. This ensures that your app runs smoothly and efficiently, providing a better user experience.
Code sharing: Kotlin Multiplatform enables developers to share Kotlin code across different platforms, significantly reducing development time and increasing code reuse. This makes the development process more efficient and cost-effective.
Flexibility: One of the key strengths of Kotlin Multiplatform is its flexibility. Developers can choose the extent of code sharing, whether it’s a small portion of the code or the entire codebase, including the UI. This allows for a tailored approach to cross-platform development.
Easy integration: Kotlin Multiplatform is based on Kotlin, making it easier for native Android developers to migrate their projects. This seamless integration ensures that developers can leverage their existing knowledge and skills, reducing the learning curve.

Real-World Applications and Success Stories

Kotlin Multiplatform has been successfully adopted by several prominent companies and developers, showcasing its effectiveness in real-world applications:

JetBrains: The creators of Kotlin themselves have used Kotlin Multiplatform to develop several applications, including the JetBrains Toolbox app. This demonstrates their confidence in the technology and its capabilities.
Google: Google has leveraged Kotlin Multiplatform to develop several applications, including the Google Maps app. By sharing code between Android and iOS platforms, they have streamlined their development process and improved efficiency.
Pinterest: Pinterest has utilized Kotlin Multiplatform to develop their mobile app, sharing code between Android and iOS platforms. This has allowed them to maintain a consistent user experience across different platforms while reducing development time.
Netflix: Netflix has also adopted Kotlin Multiplatform for their mobile app, sharing code between Android and iOS platforms. This approach has enabled them to deliver high-quality applications with native performance and reduced maintenance costs.

These success stories highlight the effectiveness of Kotlin Multiplatform in developing cross-platform applications with shared code, achieving native performance, and reducing development time and maintenance costs.

Choosing Kotlin Multiplatform for cross platform projects

Kotlin Multiplatform technology is a technology that already provides developers with powerful tools. Although it has some small issues, KMP can already be used to create applications for multiple platforms and reuse a lot of existing code, speeding up development times.

Its flexibility gives KMP an advantage over its main competitors, React Native and Flutter. Using KMP, you have better control over the functionalities on individual platforms, and you can even extend an existing application with a multiplatform module. In fact, Kotlin Multiplatform might just be the future of multiplatform development.