Flutter vs Kotlin: Which One Is Better For Cross-Platform App Development?

Vikas Agarwal

Technology and Engineering

Cross Platform App Development is necessary for businesses to create a functional application compatible with multiple operating systems. Developing usable applications for more operating systems increases the scope of download rate among users. It helps businesses cut costs and reduces development time compared to Native counterparts.

Various programming languages, libraries, frameworks, and third-party integrations are used to develop Cross-Platform Applications.

Since their release, the most popular technologies currently in use for such apps are Kotlin and Flutter.

While Kotlin is a new Programming language, Flutter is a framework that runs on Dart Code. However, Kotlin has a mobile-specific framework for developing various mobile/tablet operating systems. Both contribute to developing scalable Cross-Platform Apps that serve multiple users with respect to business logic.

For a deeper understanding, let us understand the detailed features, pros, and cons of Kotlin vs Flutter.

Flutter

Flutter is an open-source framework designed by Google in 2017. It is a cross-platform application development framework that uses the object-oriented and class-based programming language, Dart. The extensive features of this framework and its ability to provide a native-like application experience in cross-platform development make it stand out among all its competitors, like React Elements. It occupies a 3.78% market share among all apps.

Features

Single Codebase: The single codebase of Flutter allows developers to code in Dart using JIT (Just-in-time compiler) and AOT (Ahead-of-Time Compilation) that runs across Android, iOS, Windows, Linux, etc.

Flutter Architecture: The architecture involves the usage of Widgets that undergo tenderization on Skia Canvas before passing into the Platform. Flutter offers three modes with functionality- platform, engine, and framework. In Platform, there is a shell that holds Dart State Machine. The platform supports the Native Platform APIs and hosting. Its widget-like architecture offers customization to build declarative applications. It uses Native tools like Jetpack Compose and SwiftUI. The engine provides access to Skia canvas and Dart runtime, while the framework offers all the components for app development.

Easy Programming: The syntax of Flutter is similar to c-programming language. It is easier and faster to code in Flutter using the same code for responsive Android and iOS applications.

Hot Reload: Hot Reload is the main feature of Flutter that sets it apart from all other cross-platform app development technologies. This feature enables Flutter to edit the code and watch the execution in real-time. You can code at the backend, load it into Virtual Machine and review the changes in the front end. Hot Reload saves compilation time, preserves application state, and removes error vulnerabilities.

Hot Restart: This is another popular feature of Flutter that loads the code into Virtual Machine and restarts the application. The function is used post error resolutions in developing environments.

Exceptional UI: Flutter is mainly a UI toolkit that uses a rendering machine to render components to provide top-notch UI elements with declarative Native-like capabilities.

Third-Party Integration: The scope of third-party integration in Flutter is less, but it effectively collaborates with Firebase backend-as-a-service (BaaS).

Kotlin

Kotlin is a modern general-purpose statistically-typed programming language mostly used in Android app development. It is sometimes considered a “modern version of Java” that would have been developed later in the 2010 decade. Some developers call it an “upgraded Java” as it is simple, minimal, and contains fewer complexities. One of the crucial features of this programming language is Kotlin Multi-Platform which showcases native features of the developed application and its ease of integrating with other web technologies.

Features

Interoperability: Kotlin’s main feature is its Interoperability with Java and its functional cum object-oriented behavior. A Java code can be easily migrated into Kotlin due to the similarity in both languages. The conversion of code proceeds so that the application runs smoothly even during this time.

Compact Code: Kotlin’s code is a minimized version of long-form Java code. Within a few lines of code, the business logic gets executed in Kotlin. Fewer lines of code save time and budget for quality testing. The more concise the code is, the fewer errors and resolution.

Enhanced UI: The User Experience offered by Kotlin has no restrictions on development. Coders can use cross-platform and native features interchangeably to build responsive user interfaces.

Faster development: The ability of Kotlin to adhere to the target development environment and its code reusability makes it the quickest choice for developers to build apps faster.

Robust Compilation: As Kotlin is similar to Java’s object-oriented programming language nature, it has a strong compiler that powers Android and iOS.

Third-party Integration: Kotlin allows third-party integrations with libraries, frameworks, and application components.

Kotlin Multiplatform: The multi-platform of Kotlin allows developers to code for Android and iOS in a shared environment. The code for Android gets converted to Java byte code and passed on to Java Virtual Machine. In the case of iOS, the Kotlin code converts into native source code. The Kotlin code uses Kotlin Compiler into components and passes it on to the framework. These components are frontend, where Kotlin code transforms into Intermediate Representation (IR), and a backend, where IR converts to machine-executable native code.

Comparison Table of Flutter vs Kotlin

Parameter	Flutter	Kotlin
Definition	Cross-Platform App Mobile SDK Framework UI Toolkit	Object-oriented Statically-typed Programming Language
Programming Language	Dart	Kotlin
Launch	2017	2011
Developer	Google	JetBrains
Main Feature	Hot Reload and Hot Restart	Interoperability with Java
Operating systems supported	Android, Windows, iOS, macOS, Linux, Google Fuschia	Android, Windows, iOS, macOS, Linux, JVM, WebAssembly
UI design	Native-like properties with proprietary widgets	Good
Performance	Faster	Fast
Cross-Platform App Size	Large	Average
Customization	Largest	Large
Third-party integration Scope	Required but limited	Effective but not much required
Backend Scope	Integrates with Firebase for accessing Backend-as-a-service	Allows developers to directly write backend code
Testing	Extensive	Average
Community	More Extensive	Extensive
Learning Capabilities	Vast	Quick
Popular Usage	Google Ads, eBay, Alibaba, BMW, etc	Google, Pinterest, Slack, Trello, Coursera, etc

Conclusion

Depending upon the use case of the Cross-Platform Application, its size, and the purpose it serves, Kotlin is the best choice for small-size applications. In contrast, Flutter supports Minimum Viable Products (MVP) for businesses and bigger size enterprise-level ones.

If you are a new application developer, you may find Kotlin easier because of its interoperability with Java and effective asynchronous programming. Dart is an entirely new programming language similar to C, Cpp, C#, etc. Flutter provides greater customization in terms of its widget architecture, while Kotlin is a standard used for fast-android application development and is extensively used by Google for its applications.

Vikas Agarwal

Vikas Agarwal is the Founder of GrowExx, a Digital Product Development Company specializing in Product Engineering, Data Engineering, Business Intelligence, Web and Mobile Applications. His expertise lies in Technology Innovation, Product Management, Building & nurturing strong and self-managed high-performing Agile teams.