Flutter vs Kotlin Comparison: Which Is The Best Choice In 2024?

For businesses that have decided to take the plunge and build a mobile application, Flutter and Kotlin are two technologies to consider for such a project. Flutter is a cross-platform software development kit designed to build natively compiled apps for multiple platforms using a single code base. On the other hand, Kotlin is a programming language developed by JetBrains initially for Android development but is now used to develop cross-platform applications as well. 

Since Flutter is a framework and not a programming language, these two are not directly comparable. However, since they are both popular methods adopted for mobile app development, it is worth comparing how these two technologies stack up against each other. Read on our Flutter vs Kotlin comparison to see which of them is the best choice for your app development project in 2024. 

• Flutter is an open-source software development kit developed by Google for cross-platform projects.
• Kotlin is a general-purpose programming language primarily used for native Android development. 
• Flutter is an excellent choice for rapid prototyping, and for creating UI-intensive applications.
• Kotlin is more closely associated with Android mobile development, but the creation of Kotlin Multiplatform is extending the utility of this programming language into the cross-platform app development niche. 

Introduction To Flutter

Flutter is an open-source framework for building cross-platform applications. Launched in 2017 by Google, Flutter offers a complete software development kit for building mobile, desktop, and web applications all from a single codebase. 

Flutter is particularly famous for its use of prebuilt widgets to build high-performing user interfaces which speeds up the app development process. It uses Material Design widgets to implement visually appealing user interfaces based on Google’s design guidelines for the Android platform while it uses Apple’s Cupertino widgets to implement the guidelines for iOS user interfaces. 

Flutter’s primary programming language is Dart. This statically typed programming language was developed by Google and has a reactive and declarative coding model that simplifies the process of creating UIs and handling user interactions. Some of the top companies that have used Flutter to develop their apps include Google Ads, BMW, Google Pay, and Alibaba.

Apart from this Kotlin vs Flutter article, we have written several other blogs comparing Flutter to other programming languages and frameworks. You can check out our Flutter vs Native, Flutter vs Dart, and Flutter vs Swift articles to see how this multi-platform framework compares to fully native development frameworks. Conversely, our Flutter vs React Native article compares Flutter to another technology for building cross-platform apps. 

Advantages of Flutter

Cross-platform Development

Flutter is a cross-platform framework that lets you write code once while building for various platforms. The same codebase can be deployed for Android, iOS, and even desktop platforms like Windows and Linux. Since developers don’t have to rewrite code for individual platforms, building with Flutter helps with rapid development while also reducing cost and effort. It also ensures a more efficient development process since results are more consistent across the different platforms the code will be deployed.  

Native-level Performance

Although it is a cross-platform development framework. Flutter’s architecture allows it to deliver apps with native-level performance. Dart, which is the platform’s programming language, is compiled to native machine code for both Android and iOS. Flutter also has a high-performance rendering engine known as Impeller designed to optimize the rendering process in Flutter applications, leading to smoother and more responsive app performance.

Faster App Development

Flutter offers a wide range of tools to speed up the development process. One of the most important ones is the hot reload feature. With this feature, changes made to an app’s code are reflected almost immediately in the app. This speeds up the process of writing and debugging app codes. The hot reload feature also makes Flutter app development ideal for an iterative design approach where designers and testers work actively to tweak or improve the app as it is being built. 

Extensive Widget Library

In Flutter app development, the development team uses a set of prebuilt UI components known as widgets. These widgets are customizable and can be combined to create interactive user interfaces for mobile applications. The use of platform-compliant widgets allows developers to create Flutter apps that adhere to the unique requirements of the platform they’re building for.  Flutter users can also create their own widgets, giving them total control over the look and feel of their apps. 

Strong Community and Support

Flutter has become quite popular in recent years and it has a growing community built around it. Being open-source is also quite helpful in this regard since the framework benefits from frequent updates, and several plugins built by developers to improve its capabilities. Flutter also has robust documentation which makes it considerably easier for developers to learn. 

Disadvantages of Flutter

• Large App Size: Flutter apps generally come in larger sizes than native apps. This is because the entire framework and dependencies needed for the app to work on multiple platforms have to be bundled into a single app. For native apps, only platform-specific standard library functions are included in the app. The result is a large application that consumes more data space. 
• Learning Curve: Developing with Flutter means you have to learn how to use a declarative style and widget-based architecture to create apps, which can be a bit challenging. Also, Flutter developers need to learn how to code with Dart. While the language has a simple syntax that is generally easy to learn, it will take some time to fully master it. 
• Ecosystem Maturity: Flutter has a rapidly growing ecosystem. However, it is still a relatively young software development framework. This means it has a smaller community compared to older and more established native development technologies. Flutter also has fewer third-party libraries or tools available for specific use cases.

Introduction To Kotlin

Kotlin is a general-purpose programming language developed originally to replace Java for Android app development. Kotlin was created by JetBrains and released in 2011. The original purpose for creating this programming language was to fix some of the common issues associated with Java for Android development such as the verbosity of the code and null pointer errors. Consequently, Kotlin is characterized by a more concise and expressive syntax, with modern features and better development tools to speed up productivity. 

Kotlin runs on the Java Virtual Machine (JVM) and is interoperable with Java code. In 2019, Google adopted this programming language as the preferred language for building Android apps. Apart from building mobile apps, Kotlin can be used for server-side programming and building backend frameworks. Some of the companies using Kotlin for mobile app development include Uber, Trello, Kickstarter, and Pinterest.

To learn more about Kotlin, you can read other articles about this programming language on our blog. Explore our Dart vs Kotlin article to see how these two programming languages compare against each other. We also compared Kotlin to Swift in our Kotlin vs Swift article, which is interesting because they’re both used for building different kinds of native applications. 

Advantages of Kotlin

Simple and Concise

One key advantage that made Kotlin so popular among developers is its use of clean and expressive language to write code. The simple syntax of this language makes it possible to build apps while using less code compared to Java and other programming languages. Not only does this speed up development, it also makes it easier to maintain the app code. 

Secure Coding

The creators of Kotlin went the extra mile to make it more secure compared to Java. One of the ways this was achieved is by eliminating null-pointer exceptions at runtime. The programming language achieves this by distinguishing between references that can contain null and those that cannot. This results in safer and better-performing mobile apps. 

Interoperability with Java

Kotlin is fully interoperable with the Java programming language. This makes the transition from Java to Kotlin as seamless as possible. The interoperability of these two languages also makes it easy for Android developers to leverage existing Java libraries and plugins together with Kotlin on Android app development projects. This is important since Kotlin has fewer third-party libraries and tools of its own.

Disadvantages of Kotlin

• Slow compilation speed: While Kotlin is faster than older programming languages like Java, it is still slower compared to cross-platform frameworks like Flutter, especially for larger projects. This can affect the development speed and productivity of such projects. 
• Learning Curve: Kotlin has a steep learning curve, with advanced features that are generally difficult for developers to learn, especially those who are not familiar with Java and other similar languages. Also, Kotlin has less documentation and learning resources, which makes it more difficult to learn the language. 

What Is Kotlin Multiplatform?

Kotlin Multiplatform is an extension of the Kotlin programming language. It is a cross-platform development technology that allows developers to create and share codes that can be reused across multiple platforms including Android, iOS, and web applications. 

With Kotlin Multiplatform, developers can create common modules to define the logic, utility functions, and data models of applications. Once the code has been written, these modules can be deployed and used across multiple platforms. 

This will reduce the need to write platform-specific code for each operating system you’re building since the module can simply be used to implement the specific feature or User Interface design you intend to create. In addition to simplifying the development process, Kotlin Multiplatform will also help developers achieve consistency in logic and functionality across different development environments.

Advantages of Kotlin Multiplatform

Code Sharing and Reusability

The primary advantage of building apps with Kotlin Multiplatform is that it allows you to streamline the process of sharing and reusing code across multiple platforms. By writing a common code to be used across multiple platforms, developers won’t have to create a separate codebase for each platform, saving development time and cost. 

Performance Efficiency

For each platform it targets, Kotlin Multiplatform compiles code into native binaries instead of using interpreted code or virtual machines. This minimizes performance overhead so apps built with KMP deliver native performance. You can expect the same speed and responsiveness as apps built with native code like Java and Objective-C. 

Retain Platform-Specific Code

Unlike other cross-platform software development kits where you build the entire app with a single language, Kotlin Multiplatform development gives you the freedom to still use native features for each app if you want. This means you can create your Android app’s User Interface with Jetpack Compose and create the iOS app with SwiftUI. These two apps can then share the same codebase for logic and functionality using Kotlin Multiplatform. 

Disadvantages of Kotlin Multiplatform

• New project: Kotlin Multiplatform was launched recently. This means it is still a new project and still subject to changes. Also, the number of external libraries for this framework is still quite limited. Documentation is rudimentary as well, so learning how to use this SDK is a little difficult. While all of these will likely change in the future, developing with Kotlin Multiplatform is experimental at the moment. 
• Performance Overhead: In some cases, sharing code across multiple platforms can lead to some performance overhead compared to apps that are built fully with native code. However, this is often negligible, especially for non-complex applications. 

Comparison of Flutter vs Kotlin: Key Differences and Similarities

Learning Curve 

To use Flutter for mobile app development, developers have to learn Dart, which is the framework’s programming language. Just like Kotlin is related to Java, Dart is similar to C languages like Javascript and C++. For new developers with no prior knowledge of any of these languages, the additional requirement of learning the Dart programming language on top of understanding the architecture, widgets, and state management concepts of the Flutter framework presents an additional challenge. With Kotlin, you’ll only need to master the programming language alone, which will be easier if you’re already familiar with Java. 

Community Support

Flutter and Kotlin are both rapidly gaining popularity. Currently, millions of developers are part of the platform’s open-source community. However, when you compare the size and maturity of the ecosystem, Flutter overtakes Kotlin. It has more active members contributing to the platform’s codebase and developing components for the framework. 

Performance

Flutter uses the Dart programming language which compiles with Just-in-Time and Ahead-of-Time capabilities. The compilation mechanism of Flutter apps enhances their efficiency and overall performance. However, while Flutter offers excellent performance, the fact that it requires an extra layer of abstraction might lead to a slight performance overhead compared to native apps. Kotlin on the other hand compiles code in a format that matches the platform’s requirements especially when it is used for native development. The performance capabilities increase significantly with this mechanism.

Development Speed

Flutter offers prebuilt widgets and other components that give developers an enriched experience. The fact that you don’t have to write codes for each platform thanks to the platform’s cross-platform functionality also helps to save time and resources. With Flutter, you can build apps for Android, iOS, and desktop from just a single code base. Developers also love the platform’s hot reload feature because it allows them to see changes made to the code instantly. This improves productivity and speeds up development. 

While Kotlin is generally efficient for app development, building for just Android alone wastes time and resources especially if the goal is to build for iOS as well. The invention of Kotlin Multiplatform, which has cross-platform capabilities has helped to change this. Instead of duplicating each piece of code for Android and iOS apps, KMP supports code reusability. In this case, developers only need to write the code for business logic and app functionality once. This code can then be reused again and again across multiple platforms, saving time, and cost of development as well. 

UI Development

In Flutter, user interfaces are built using prebuilt UI widgets and declarative UI paradigms which involves simply defining the desired state of the user interface while the framework itself handles the rendering and state transitions. This approach to UI development is generally more intuitive and efficient compared to the alternative. 

Kotlin is a statically typed language that uses a more manual approach to UI development where you have to explicitly write out platform-specific UI code to manipulate UI elements. Although this approach gives developers greater control over the UI elements so they can manipulate them manually, it is a slower way to develop user interfaces and can get quite cumbersome, especially for complex apps.

When to Choose Flutter Over Kotlin?

• Cross-platform application for major mobile platforms (iOS and Android) operating systems on a single codebase
• Rapid prototyping and development especially for smaller projects
• Apps with complex animations and UI
• Web and desktop app development

When to Choose Kotlin Over Flutter?

• Building high-quality applications for Android devices 
• Performance-critical apps (especially those that require extensive interaction with native platform APIs or features) 
• Working with existing Java codebases with seamless integration
• Smaller and simpler projects 
• Cross-platform development (using Kotlin Multiplatform)

Future of Android App Development with Flutter and Kotlin Programming Languages

The world of mobile app development is a constant path of evolution. Although Flutter and Kotlin have emerged as the most prominent contenders for building mobile apps, there’s no telling what the future holds for each of them. 

Flutter is a relatively young cross-platform framework that relies on third-party plugins, packages, and components to extend its capabilities. As the Flutter ecosystem continues to mature, there will be more of these packages to optimize the process of building apps with this framework. Google and Flutter’s open-source community are actively working to enhance the platform’s capabilities, especially for web and desktop app development. In the future, Flutter will probably grow even more versatile and several new platforms will be integrated into it. 

Flutter is also poised to adopt many new technologies and improvements in the future. For instance, Google recently announced plans to integrate Flutter with its machine-learning tools to help create intelligent and personalized applications. 

Kotlin, being an older programming language has already established itself as a mature and well-supported tool, especially for native Android app development. It is likely to remain strong in this area. 

The future will likely see a greater focus on Kotlin Multiplatform, a relatively new extension of the Kotlin ecosystem that will allow the language to establish itself in the cross-platform niche. Of course, Kotlin Multiplatform is still a long way from competing with more established cross-platform frameworks like Flutter with a mature ecosystem.

Conclusion

Kotlin and Flutter are two promising tools for building mobile applications. Considering their similarities and differences, their suitability for a particular project depends on the peculiarities of the project such as the type of app, complexity, development cost, and so on. 

If you’re still uncertain about which framework or programming language to use for your project between Flutter vs Kotlin, our software development team can help. We have proven expertise and experience in building apps with Flutter and Kotlin and can help you choose a programming language or framework that meets all your performance and functionality needs. Contact us today to get started with your next app development project with Kotlin or Flutter.