Online Kotlin Compiler

Write and run Kotlin code directly in your browser with this free online compiler. Kotlin is a modern language developed by JetBrains that runs on the JVM and is the preferred language for Android development. It combines object-oriented and functional programming with a clean, concise syntax. This compiler lets you execute Kotlin code instantly without installing any tools.

What is Kotlin?

Kotlin is a statically typed programming language developed by JetBrains in 2011 and officially supported by Google for Android development since 2017. It is fully interoperable with Java and runs on the JVM, JavaScript, and native platforms. Kotlin addresses many of Java's pain points with features like null safety, data classes, extension functions, coroutines, and concise syntax. It has become the language of choice for Android app development and is also used for backend development with Ktor and multiplatform projects.

Key Features

• Null Safety: Type system eliminates null pointer exceptions.
• Concise Syntax: Less boilerplate code than Java.
• Coroutines: Built-in support for asynchronous programming.
• Data Classes: Automatic toString, equals, hashCode, and copy methods.
• Java Interoperable: Works seamlessly with existing Java code.

Basic Kotlin Syntax

// Data class
data class Developer(val name: String) {
    fun greet() = println("Welcome, $name!")
}

fun main() {
    // Variables
    val site = "LabsICT"
    val year = 2025

    // List and loop
    val languages = listOf("Kotlin", "Python", "Java")
    languages.forEach { lang ->
        println("Learn $lang at $site")
    }

    // Object usage
    val dev = Developer("Bilal")
    dev.greet()

    // Null safety
    val nullable: String? = null
    println(nullable ?: "No value")
}

What Can You Build with Kotlin?

Kotlin is the official language for Android app development, used by companies like Google, Pinterest, Uber, and Trello. Backend developers use Ktor and Spring Boot with Kotlin to build REST APIs and microservices. Kotlin Multiplatform enables sharing code between Android, iOS, web, and desktop. It is also used for server-side applications, scripting, and building CLI tools.

Try It Yourself

Type your Kotlin code in the editor and click Run. The compiler supports standard Kotlin features including data classes, extension functions, lambdas, null safety, and coroutines. Use Copy to save, Reset to restore the example, and Share to generate a link.

Related Resources

Continue with our Kotlin learning track, try more online compilers, or browse tutorials for step-by-step guides.