Flutter vs Kotlin Multiplatform: What’s Better for Your App?

When you need to hire developers for your app, choosing the right technology from the start is crucial. Many companies face a key decision: should the app be built natively for iOS and Android, or should they use a cross-platform solution like Flutter or Kotlin Multiplatform (KMP)?

The choice affects not only development speed but also how efficiently your outsourced team can deliver updates, scale features, and maintain performance. Cross-platform development is becoming increasingly popular for teams that need to move fast, save costs, and rely on one codebase for multiple platforms.

In this guide, you’ll learn the main differences between Flutter and KMP, what to consider when outsourcing developers, and how to choose the technology that best fits your project’s needs.

Why Cross-Platform Development Makes Sense for Outsourcing?

Let me be straight with you: if your goal is to hire developers to get an app done efficiently, cross-platform development is where it makes sense. Instead of maintaining separate teams for iOS and Android, you get one codebase that works everywhere, which saves time, money, and headaches.

Today, it’s not just Flutter and Kotlin Multiplatform anymore. Compose Multiplatform (CMP) is also coming up strong. The cool thing about CMP is that you can share business logic and even UI components between iOS and Android while keeping everything native-looking. That’s huge if you want a high-performing app without doubling the team.

The reality is, outsourcing a cross-platform team, whether they’re Flutter, KMP, or CMP experts, lets you move faster, keep development costs under control, and get quality close to native. And if you pick the right team, they can also give you smart advice on architecture and scaling, not just push code.

Cross-platform app can't make native performance: Myth or truth?

A lot of enterprises are hesitant about cross-platform apps because they worry it will crash, break, or behave inconsistently on iOS vs Android. I get it, when you’re managing large-scale apps, even small inconsistencies can cost time and money.

The beauty of Kotlin Multiplatform is that you don’t have to rewrite the whole app from scratch. You can migrate part by part, which minimizes risk and keeps the rest of your app stable. I recently did this for a client’s analytics: by creating a KMP analytics library, I ensured consistent tracking across iOS and Android, avoided duplicated events, and fixed minor inconsistencies, all without touching the rest of the app.

I wrote a separate blog post for this: Adding KMP to an Existing Native App

This approach makes cross-platform development enterprise-friendly, letting your outsourced team gradually improve performance, maintain stability, and deliver high-quality features faster.

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Why does Netflix use Kotlin Multiplatform?

Netflix uses Kotlin Multiplatform because it allows them to share code across Android, iOS, web, and desktop while keeping native performance where it matters. Depending on the project, KMP can handle shared logic, full business logic, or even parts of the UI.

For companies looking to hire Kotlin Multiplatform developers, this approach means you can reduce duplicated work, maintain app stability, and accelerate feature delivery across platforms. If you’re outsourcing a mobile project, using KMP lets your team migrate parts of an existing app gradually, fix inconsistencies, and scale without breaking what already works, just like Netflix does.

KMP advantages

Independent integration:

Kotlin is an SDK rather than a framework. What does it mean? Businesses with mobile apps can easily evaluate their potential by adding a module or migrating a few features. This significantly helps Kotlin in addressing the main obstacle to switching to a new codebase.

Cost-effectiveness:

Cross platform app development reduces the time required for building mobile apps by minimizing the need for separate iOS/Android development teams, thus lowering development and maintenance costs.

Native performance:

Kotlin Multiplatform allows direct access to native APIs and libraries. It means developers can implement custom features and write native code that is unique to each platform. That way KMP takes advantage of the latest platform-specific functionalities and provides a rich user experience with cross platform apps.

Separate UI development:

Developers can use platform-specific native UI components and provide tailored functionalities for iOS and Android. By creating separate UI for each platform, users get that “native feeling", meaning they have intuitive and familiar behavior since some things work differently for iOS and Android.

KMP challenges

Investment in adopting KMP:

Developers who are not already familiar with Kotlin or cross-platform development concepts need to understand how to effectively share code across platforms. However, the growing community and extensive documentation are valuable resources that can help ease this transition.

Development time:

Developers need to implement separate UI, and that can lead to increased development time and effort for creating and maintaining multiple user interface codebases. Still, it is a faster option than not sharing a business logic.

New and still maturing:

Compared to some other cross-platform frameworks, this implies less prepared libraries and plugins, but it also offers an ideal opportunity to grow on cutting-edge technology that is quickly gaining popularity and support.

Having considered all the pros and cons, Netflix decided to use Kotlin Multiplatform for its studio applications, enabling the team to share business logic across platforms while maintaining native user interfaces and performance. With a shared codebase, Netflix develops features once and deploys them across various platforms, speeding up the mobile app development process.

What is Flutter?

Flutter, created by Google, is an open-source framework that enables developers to build natively compiled applications for mobile, web, and desktop from a single codebase using the Dart programming language.

Flutter advantages

Hot reload feature:

This allows developers to instantly view changes without restarting the app, which speeds up the development process.

UI/UX capabilities:

Flutter has a rich set of customizable widgets, which allow developers to create highly flexible and visually appealing user interfaces that provide a consistent experience across all platforms.

Single codebase:

Developers write code once and deploy it on multiple platforms such as iOS, Android, web, and desktop. It means there is a code that covers both business logic and UI. This approach significantly reduces development time, effort, and costs.

Strong community and support:

The developer community around Flutter is big, matching the size and activity of communities behind other well-known frameworks such as React Native. With frequent updates, bug updates, and the launch of new features, this vibrant community helps Flutter evolve quickly.

Flutter challenges

Large app size:

Flutter includes its own set of UI components which makes the app size larger than the native ones. Kotlin Multiplatform and React Native tend to have smaller app sizes since they support native components provided by the platform.

New language:

Dart is a completely new language used for Flutter and it may bring challenges compared to more established languages like JavaScript or Python. Developers may find fewer resources which makes it harder to find solutions.

Limited Native flexibility:

In case developers need highly tailored or platform-specific implementations that aren't easily found in the Flutter community, they might have to rely on third-party solutions or write platform-specific code, which might complicate the development process.

So, what is the best choice to make?

If you’re trying to decide between KMP and Flutter, here’s what I usually tell people I work with.

KMP works best for apps where you need native-level performance on both iOS and Android and want to share core logic without compromising the experience on either platform. For example, think of a complex enterprise app with heavy data processing, custom animations, or multiple integrations. KMP lets your outsourced team maintain performance while reusing code for business logic across platforms.

Flutter, on the other hand, is perfect when your app doesn’t rely heavily on platform-specific features. Imagine a marketing app, an e-commerce catalog, or a simple booking tool: one codebase covers iOS, Android, web, and even desktop, so your team can launch faster while keeping the app consistent and visually appealing everywhere.

At Aetherius, we’ve built apps using KMP, Flutter, and other cross-platform technologies, tailoring the approach to each project’s needs. For instance, some clients needed high-performance apps for internal enterprise use (we used KMP), while others wanted quick-to-market apps with a consistent UI for multiple platforms (we used Flutter). You can see these examples and more on our portfolio page.

Ready to build cross platform mobile apps?

If this article helped you understand which cross-platform framework fits your project, you’re in the right place. At Aetherius, our cross-platform development teams can be onboarded in max of 5 days, letting you see progress quickly while keeping your project on track.

Prefer native development? Our iOS and Android developers will ensure your app runs flawlessly, performs reliably, and scales smoothly, while helping you get the right users on board.

Whether it’s cross-platform or native, we provide experienced developers and proven processes to bring your project to life on time and on budget. Contact us and let's see how we can help with the project!