Kotlin vs. Flutter Multiplatform: Which is Best for Your App?

November 20, 2023

Mobile applications have become indispensable in today's digital world. According to App Annie, mobile app downloads are projected to reach 352 billion downloads and consumer spend on apps will surpass $270 billion by 2025. This exponential growth underscores the need for robust and efficient tools for building mobile apps.

In this highly competitive landscape, cross-platform frameworks have emerged as attractive options for developing mobile apps. Instead of building native apps separately for iOS and Android, cross-platform tools allow developers to use a single codebase to release apps on multiple platforms. This promises significant time and cost savings.

This article focuses on comparing two of the most popular cross-platform mobile development frameworks - Kotlin Multiplatform and Flutter. We will dive into the features and capabilities of both to help you determine the right fit for your next mobile app project.

Understanding Cross-Platform Application Development

Cross-platform application development refers to building mobile and desktop apps that can run on multiple operating systems and devices. For instance, a cross-platform mobile app can run on both Android and iOS platforms.

The main benefit of cross-platform development is the ability to use a single codebase to build apps for different platforms. This results in faster time-to-market since developers don't have to recreate the app natively for each platform. It also reduces development and maintenance costs.

Another advantage is being able to reach a wider audience across platforms without having to release platform-specific app versions. Cross-platform apps also make it easier to maintain feature parity and synchronization across different app versions.

Overall, cross-platform development maximizes code reuse, minimizes fragmentation, and streamlines the development process. However, some compromises in leveraging native capabilities may be required.

Challenges in Cross-Platform Development

While cross-platform development has its merits, there are some inherent challenges:

  • •   Platform-specific capabilities - Native APIs and SDKs allow better access to unique device features like camera, GPS etc. This may be restricted in cross-platform apps.
  • •   User experience - Each platform has its own UI/UX design guidelines. Cross-platform tools may not always adhere to these, resulting in sub-optimal UX.
  • •   Fragmentation - Supporting a wide variety of devices with varying capabilities can be difficult with a single codebase.
  • •   Testing and debugging - Testing on all target platforms requires significant additional effort. Bugs might manifest differently across platforms.
  • •   Performance - Cross-platform apps may reflect performance lags compared to natively built apps.

Overcoming these challenges requires cross-platform tools to be highly refined, efficient and versatile. Let's evaluate how Kotlin and Flutter measure up on this front.

What is Kotlin Multiplatform?

Kotlin Multiplatform is a framework from JetBrains that extends the Kotlin programming language for cross-platform development. It allows using Kotlin code and shared logic across different platforms like Android, iOS, JavaScript, Windows, Linux etc.

Kotlin offers a modern, concise language that interoperates seamlessly with Java. Kotlin Multiplatform combines this with a shared programming paradigm to build apps for different targets from the same code. It provides access to native platform capabilities via platform-specific APIs.

While still evolving, Kotlin Multiplatform has seen increased adoption. JetBrains is actively working on expanding its capabilities for iOS and improving JavaScript support. The future looks bright for Kotlin to become a leading cross-platform solution.

What is Flutter?

Flutter is Google’s free, open-source SDK for building beautiful, high-performance mobile apps for iOS and Android from a single Dart codebase. It provides reactive frameworks, extensive widget libraries, asynchronous programming support and Dart developer tools.

Flutter features fast development cycles, excellent documentation, a customizable widget set and full-stack capabilities for end-to-end native app development. Its high-quality visual rendering engine draws at 120fps delivering interactions and animations that feel natural on both platforms.

Flutter's popularity has skyrocketed globally with developers drawn to its rich reactive framework, stateful Hot Reload for instant UI updates and impressive ready-to-use widget implementations. Integrating Flutter with existing code is relatively smooth.

Comparing Apples to Oranges: Kotlin vs. Flutter

Let's pit Kotlin Multiplatform and Flutter head-to-head across some key parameters:


  • •  Flutter delivers flawless UI performance with its polished rendering engine while Kotlin is still strengthening its multi-threaded architecture.

UI Experience

  • •  Flutter's extensive widget set enables pixel-perfect, customizable UI design adhering to native guidelines. Kotlin provides UI layer flexibility but lags a bit on ready widgets.


  • •  Both Kotlin and Flutter offer free open-source SDKs and tools bringing cost benefits versus native development.


  • •  Flutter leads here with surging adoption among developers. Kotlin Multiplatform is catching up with growing community support.

Learning Curve

  • •  Kotlin's similarity with Java makes it relatively easy to learn. Flutter's declarative Dart syntax has a steeper learning curve.

Community & Support

  • •  Flutter has abundant documentation, guides and an engaged community. Kotlin Multiplatform's ecosystem is still maturing.


  • •  Out-of-the-box, Flutter can enable faster app development cycles once developers are proficient with it.

Head-to-Head Showdown


Kotlin Multiplatform



Kotlin (Interoperable with Java)


Developer Support






UI/UX Capabilities



Testing Support






Backend Development Capabilities

Full stack

Possible via plugins

Notable Apps Using Framework

Turbopascal, Wallapop

Alibaba, Google Ads

User Ratings on Stack Overflow

78% positive

85% positive

Final Verdict

To summarize, Flutter leads Kotlin Multiplatform across many parameters at this point in time. Its refined toolkit, engaging community support and excellent performance make Flutter a lucrative cross-platform solution today.

However, Kotlin Multiplatform is catching up with its interoperability with Java, ease of learning Kotlin and expanding platform support. It shows potential to give Flutter tough competition in future.

For apps with complex visuals and animations, Flutter seems favorable. Kotlin may be preferable if Java integration is a priority. Both can enable cost and time efficiencies versus native development.

Ultimately, the needs of the app and team capabilities should drive the framework selection. Both Kotlin and Flutter are evolving rapidly and offer versatile options for cross-platform development.


This comparison highlights that Kotlin Multiplatform and Flutter have their own strengths and shortcomings for cross-platform mobile development. There is no clear winner - the most suitable option depends on the app requirements, target platforms, development skills and resources.

While Flutter currently edges ahead on many aspects, Kotlin Multiplatform is strengthening its ecosystem and tooling. Both continue to broaden the possibilities for building high-quality mobile apps more efficiently.

As developers, we are fortunate to have these advanced frameworks push the boundaries further. Trying out both first-hand can provide the best perspective into what resonates with your needs. This exploration will undoubtedly reveal promising possibilities to build the next big mobile experience on your horizon!

I hope this breakdown has provided a structured overview of Kotlin and Flutter. Please share your thoughts or experiences with these frameworks. Your insights could help other developers make informed choices for their mobile projects!