Flutter vs Kotlin: Choose The Best One For Cross-Platform App Development

Table of Contents

Flutter vs Kotlin: Head-To-Head Comparison

With the increasing popularity of cross-platform application development, the three leading frameworks: Flutter, React Native, and Kotlin, are always in a heated dilemma. However, Flutter vs Kotlin is the comparison that catches the attention of many businesses looking to scale up their cross-platform application. Before moving to the introduction of both cross-platform app development tech stacks, let us have a glance through the quick head-to-head comparison of Kotlin vs Flutter in 2023.

Introduction To Flutter

Flutter is Google’s open-source and cross-platform UI development toolkit to create mobile, web, and desktop applications from a single codebase. It utilized Dart as the programming language that uses Ahead-of-time (AOT) compilation. Flutter overcame the challenges faced by mobile and web app developers face and became the ideal cross-platform app development framework.

The flutter architecture is based on the widgets that are rendered on Skia Canvas. These widgets are then sent to the platform, which shows the canvas and sends the events back as per requirement. The Flutter architecture involves three components, as mentioned below:

Platform: The Flutter offers a Shell that holds the Dart Virtual Machine. The Shell is platform-specific, giving access to the native platform’s relevant canvas.

Engine: The Engine provides Dart runtime, Skia platform Channels, and more. The relevant Flutter engine runs inside the appropriate platform shell.

Framework: This layer possesses all the components needed to develop the app for the developers.

Flutter Features

Hot Reload

Whenever the developer modifies/changes the code, the Hot Reload will instantly reflect the changes, allowing the programmers to identify and fix the bugs easily.

Widgets-Based Infrastructure

In order to provide a flawless experience on all platforms, Flutter utilizes two widget sets, namely, Material Designs and Cupertino Widgets.

Open-Source

To create impeccable mobile applications, you will not have to pay a dime to get the code, as Flutter is an open-source framework.

Native Features Accessibility

It will be possible to access the native code, third-party integrations, and platform APIs when using Flutter for cross-platform application development.

Minimal Coding

Flutter uses the Dart programming language along with JIT and AOT compilation to enhance the app’s overall development, functionality, and performance.

Platform Specific Logic Implementation

The developers can write the code specific to the platform defined for the application development.

Usage Statistics

Being an open-source and popular cross-platform app development framework, Flutter is growing rapidly. Have a look at the below usage statistics.

🟠 As of 2023, Flutter has 517,528 repository results, 152K stars, and 25.2K forks on GitHub.
🟠 According to BuiltWith, over 56,593 websites developed using Flutter and around 16,000 sites built historically.

Pros and Cons of Flutter

Pros

Fast Prototype
With the help of the hot reload feature, the developers can easily code and make real-time changes as per requirements without restarting the application during app development in Flutter. One can inject the source code into the app even when the app is running. The widget tree is automatically built by Flutter, which allows real-time changes to show up. Hence, you will get a faster and more effective result.

Fewer Codes
As Flutter uses the Dart language for app development, it follows a declarative and reactive programming style to avoid the JavaScript bridge’s necessity. As a result, it enhances the performance of the app along with reducing startup time. With the AOT and JIT compilation, it will be possible to streamline the development workflow and eliminate the necessity of building the UI from scratch.

Reliable Native Support
Flutter developers are indeed in love with the technology as they have created a great community to assist and support in terms of everything. Whether it is scrolling speed or performance for which you are facing issues in the development, Flutter provides you with reliable and great native support. Flutter’s app performance is very close to native applications with more complex and interactive UIs.

Ideal for MVPs
When you need to complete the app development project quickly, within a short deadline, Flutter is the best choice. The mobile app development in Flutter can help you get a proper insight into the idea and purpose of the product and how the end product will function and appear after MVP development. This will save you a considerable amount of time and money.

Cons

Limited Libraries
Although Flutter possesses several essential libraries, you cannot find all the functionalities as per requirements. However, Flutter native apps have all the functionalities in their SDKs, including Twilio, Stripe, and services like UStream and WoWza. Native apps come with all the functionalities in their SDKs, and it requires the developers to use Flutter for developing these libraries, which is time-consuming.

App Size
Flutter creates apps larger than 4 MB in size or more, making it a concern for business owners who intend to develop a smaller app with minimal size. Although Google’s team is working continuously to improve this issue in Flutter, this could be a time taking process. The core reason behind this large app size is the inbuilt widgets which make the app size large.

Unstable
As Flutter is comparatively newer in the marketplace, you need to consider the possibility of the technology being unstable. This can be realized by the community reviews, which raise concerns like coping with the changes in the UI of Android and iOS. A few developer community members also suggest that Flutter should be able to handle larger eCommerce applications.

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Introduction To Kotlin

Kotlin, as you know, is a general-purpose cross-platform programming language using which developers can share data, code, and business logic across Android, iOS, JVM, macOS, Linux, and the Web. Developed by JetBrains in 2016, Kotlin can be utilized to work with various platforms and hence, is known as Kotlin Multiplatform. Due to its simplicity, efficient performance, and ease of use, most business owners prefer to choose Kotlin as their cross-platform app development technology.

Based on recent statistics, over 100K apps have been built using the Kotlin programming language though it is considerably new. We can deduce the growing popularity and traction of Kotlin from such statistics and data. Also, many popular brand names like Chalk, Autodesk, Yandex, Touchlab, Icerock, and Vmware are using Kotlin to build cross-platform applications and solutions. Hence, it would be a wise choice to consider Kotlin, the second most popular cross-platform programming language after Java.

Kotlin Features

Conciseness in Coding

Utilizing the Kotlin programming language, developers get the freedom to eliminate writing extra lines of code, making the code structure more concise.

Null Safety

Being a null safety language, Kotlin features the removing the NullPointerException from the code.Interoperable, helping the programmers to code effectively.

Interactive

This feature allows Kotlin programmers to easily call the Java code to execute any functionality. Also, it allows Java to interact with Kotlin, so there is no need to write code functions again.

Smart Cast

Utilizing Kotlin for cross-platform app development, you will get the smart cast feature that efficiently typecasts the fixed values and shifts the value to the safe cast.

Feasible With Tools

As several tools are available, you can use tools during developing mobile applications in Kotlin to create functions using the command line or Java IDE.

Extensions

Well, the extension functions and properties assist in expanding the limitations of the functions and operations without changing or modifying the code.

Usage Statistics

🟠 Currently, there are over 259,173 repository results with 44.5K stars and 5.5K forks available on GitHub.
🟠 According to StackOverflow, Kotlin holds the 15th position in the most popular technologies, with 9.16% votes.

Kotlin Pros and Cons

Pros

Java Compatibility
When using Kotlin, you should know that it is a genuinely interoperable language that allows for preserving a fair part of Java’s object-oriented nature. So, writing or migrating the code to the Kotlin language is easy and simple. Not only will it enable managing old apps with Java and building new Kotlin ones, but it will also convert the apps easily without affecting the process. It offers outstanding compatibility with Java which helps Kotlin developers in multiple ways.

Minimized Bugs
Kotlin possesses a simple syntax that offers a much clearer and more compact codebase that makes the code in production more stable and consistent. As you know, fewer lines of code mean fewer bugs, leading to faster and more efficient development. Simplified and clean development helps developers to detect bugs when compiling the code so they can fix them before executing the code.

Easy to Maintain
Many IDEs like Android Studio and other SDK tools are in favor of Kotlin. The development of mobile applications and functions is easily maintained when using Kotlin. It will ensure improved productivity of developers as they can continue to work with the toolkit they are familiar with.

Cons

Fewer Resources
As Kotlin is a relatively new language, there are only limited resources available as compared to other programming languages. Though Kotlin has gained significant popularity recently, only a limited number of professionals in the market are actual experts and have in-depth knowledge of Kotlin.

Expensive
The cost of the development is high for Kotlin as it presents only a semi-native SDK functionality, making it a bit more expensive. For Prototypes and MVPs, the development is costly and uneconomical because the developers need to take considerable time to learn the new language and its functionalities.

Compilation Takes Time
Kotlin offers a comparatively slower compilation than Flutter. The compilation process requires time as there are several components that do not have the capability to execute functions like Java rapidly. Hence, Kotlin’s slower compilation speed is a significant factor to consider when using it for mobile application development.

How Kotlin Multiplatform Can Benefit Cross-Platform App Development?

Kotlin Multiplatform is a software development kit developed and introduced by Google’s cross-platform mobile development team. Kotlin multiplatform, as the name suggests, allows developers to utilize Kotlin efficiently for different platforms like iOS and Android simultaneously. With Kotlin Multiplatform, you can utilize Kotlin developers who have worked with Android Kotlin-based apps to deploy the application to iOS without investing in additional workers having experience with Swift, Flutter, or React Native. Let’s look at how Kotlin Multiplatform can help cross-platform app development.

Rapid Development

Using Kotlin Multiplatform, you can achieve faster development as developers can add model objects, networking, business logic, and plugin the features simultaneously. Parallel operations can accelerate the development process.

Improved Code Quality

You can get an improved code quality as Kotlin Multiplatform allows early bug detection, resolving, and functional consistency between the app functions during the development.

Easy Code Maintenance

Due to the code modularity and maintainable code, it will be easy for any new developer to get a better understanding of the codebase, leading to less back and forth and minimized confusion.

Flutter vs Kotlin: In-Depth Comparison

Now, you may have a better understanding of both the platforms, Flutter and Kotlin. So, let us dive deeper into the in-depth comparison of Flutter vs Kotlin to help you decide which is better for cross-platform application development.

Performance

As mentioned earlier, Flutter uses Dart programming language to offer quick compilation, execution, and development of the application. Also, it offers hot reload features that allow developers to simultaneously modify the backend as well as view the changes in the front end. On the other hand, Kotlin offers compatibility with various platforms, allowing developers to compile in the same format as that of the target application. This feature of Kotlin makes it earn the efficient performance of the apps and win the battle of performance.

Popularity

When comparing Flutter vs Kotlin popularity, we can believe that Flutter has got the upper hand over Kotlin. Flutter has a huge community on GitHub with 146k Stars and 23.5k Forks, whereas Kotlin has a comparatively small community with 42.8k Stars and 5.3k Forks. To get a better insight into the popularity and growing traction of Flutter and Kotlin, you can look at the below image of Google Trends that concludes the victory of Flutter in terms of popularity.

Community Support

As Google backs Flutter, it has a thriving open-source community of tech enthusiasts that are always looking for opportunities to help or assist regarding application development. The user base of Flutter is gradually growing, and it is a top choice for many famous organizations and enterprises. In comparison, Kotlin also has increased quite a stable and mature community of mobile app developers. Kotlin is constantly evolving with a rich community and is now an official language used for Android application development. Both platforms have a reliable and active community which leads to a tie in comparison between Kotlin vs Flutter.

UI Experience

UI Experience, as you know, plays a significant role in cross-platform app development. Using Kotlin, UI designers can work on the app’s appearance, behavior, and performance just as they want due to the programming language’s freedom and flexibility. Kotlin does not bind developers with any conditions, allowing them to use their native libraries and tools rather than building new ones. On the other hand, Flutter is an SDK that primarily enables UI development tools and offers various in-built widgets to create flawless applications. With Flutter, developers can build speedy mobile solutions with a custom look and feel.

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Testing Support

Flutter comes with good value testing features to test widgets, app integration, and unit testing. The well-described documentation is an added advantage as it helps convey the instructions related to testing the functionality and features. The widget testing feature of Flutter enables users to unit test the widgets. Flutter operates on Firebase, a backend-as-a-service tool. In comparison, integrating various widgets and tools is not essential for Kotlin. To test various functionalities, Kotlin allows developers to use their native tools for cross-platform testing as well.

Integration

Flutter integrates quickly and efficiently with both Android and iOS platforms, which makes Flutter a perfect choice for building a minimum viable product MVP. Integration is not a problem with Flutter, but with Kotlin, users don’t need to integrate. Yes, that’s right! Kotlin provides a multiplatform which enables users to work within their native framework. Hence, there is no need for integration, and developers can use their native libraries and tools for their cross-platform apps. So, Kotlin is announced to be the winner for the integration comparison of Kotlin vs Flutter.

Supported Platforms

When you select Flutter for cross-platform app development, it allows users to create interactive and efficient mobile applications (Android and iOS) and web applications. However, Flutter does not support television (tvOS), Android Auto, CarOS, or smartwatch OS. On the other side, Kotlin provides no constraints to developers, who can use Kotlin for platforms beyond mobile, like television, smartwatch, etc. Hence, Kotlin is a wise choice for multiplatform app development as it supports a greater number of platforms than Flutter.

Documentation

Be it Flutter or Kotlin; both should offer well-structured and organized documentation to help developers understand the fundamentals. In terms of documentation, Flutter is open-source and free to use, allowing it to provide extensive and detailed documentation. Also, Flutter offers a set of testing functions that unit-test the widget while integrating the level along with significant testing documentation for widget testing. So, the developers can create widget tests to try the UI and run them at the speed of unit testing. On the other hand, Kotlin lags in the documentation. However, the documentation of Kotlin is expected to improve over time with respect to stability and readability.

Learning Curve

Comparing Flutter vs Kotlin in terms of their learning curves, Kotlin has a simple and easy learning curve. Kotlin is quite easy to learn for developers because once you know Java, it is pretty similar to it. Having familiarity with Java, you can conveniently try your hands on Kotlin. Flutter uses Dart programming language, making it easy to learn. Developed by Google, Flutter has a low learning curve, making it easier for developers to have familiarity with Python, JavaScript, C++, and C#.

Time To Market

Flutter offers a hot reload, enabling faster testing and changes per requirements, resulting in more rapid UI development. Using Flutter, you will get to utilize various widgets, customized features, and layered architecture that allows delivering native-like user experiences at a faster pace. Comparatively, Flutter is faster than Kotlin. Though Kotlin possesses more features like its concise syntax and code reusability, Flutter offers more rapid app development along with a shorter market time. Flutter wins it, but still, both Flutter and Kotlin save development time to a great extent by using a single codebase for developing multiplatform apps.

User Friendliness

When talking about user-friendliness, both Kotlin and Flutter offer an almost native-like experience. Flutter provides a unified user experience on all platforms. Being a widget-based cross-platform framework, Flutter comes with some great options to customize the app, allowing for a functional and scalable product. On the other hand, Kotlin allows smooth app development utilizing its general-purpose programming language, especially when developing Android apps. Kotlin app developers have full power to build tailor-made UIs that fit the business objectives and the development scope.

Frontend and Backend Capabilities

Flutter leverages the full potential of Firebase to write code in the backend. Hence, it is renowned for its beautiful UI development capabilities. In terms of development, using Flutter is simple, easy, and efficient. The SDK offers a range of customization options via widgets. Though Flutter is ideal to use for front-end development, it provides significant support for the backend. While Kotlin is a general-purpose language that offers great flexibility for developers to create apps per their needs and requirements, Kotlin is a perfect choice if you want to develop large and complex apps.

Popular Apps Based on Flutter and Kotlin

Apps Built With Flutter

🟠 GoogleAds
🟠 Alibaba
🟠 BMW
🟠 eBay
🟠 SpaceX Go
🟠 Cred

Apps Built With Kotlin

🟠 Airbnb
🟠 Evernote
🟠 Trello
🟠 Slack
🟠 Pinterest
🟠 Netflix

Kotlin vs Flutter: When To Use What?

Kotlin and Flutter, both cross-platform app development platforms, have their own benefits and drawbacks. However, the key factors mentioned in the comparison above can help you select the right one for mobile application development. Although we have covered several parameters to compare Flutter vs Kotlin, here is the simple and quick differentiation of when and what platform to prefer.

When To Use Flutter?

It will be beneficial to choose Flutter if you need,

• Developing an MVP product or prototype model
• Building a performant, time-efficient, and cost-effective solution
• Create small, medium, or large business applications
• Rapid application development within a short deadline
• Visually appealing and interactive user interface
• App development with native-like features, including Geo-location, Camera, etc.

When To Use Kotlin?

Selecting Kotlin would be a wise choice when you need,

• Revamping or modifying the existing applications
• To write heavy and sophisticated codes
• Building an alternative cross-platform application to your large-size application
• Cross-platform application integration
• Quick bug detection and fixes
• Writing server-side code efficiently and smoothly

Conclusion

Frequently Asked Questions (FAQs)

What are the benefits of using cross-platform apps?

There are several benefits you will get by using cross-platform mobile application development, including but not limited to quick turnaround time, cost-effective development, easy deployment, smoother workflow, and a short time to market.

Is Flutter better than Kotlin for app development?

Well, both Flutter and Kotlin excel at their own parameters. So, it totally depends on your project requirements or application needs whether Flutter or Kotlin will be a better choice. Flutter is proven to be the best choice for developing an MVP product or prototype model. At the same time, Kotlin is mostly preferred for developing Android applications.

Which is easier to learn: Flutter or Kotlin?

Learning Kotlin programming language would be easy and quick for developers familiar with Java syntax. On the other hand, Flutter uses Dart programming language, which makes it easier to learn for any new developers. Overall, both platforms are not too difficult to learn if given the right amount of time and dedication.

Can Kotlin be used for Android application development?

Yes, it will be a perfect decision to use Kotlin for Android app development. Kotlin is the official language to build Android apps as it works smoothly with Java and ensures concise syntax, precise coding, and secure operations.