An online Kotlin compiler is a web-based tool that allows users to write, edit, and execute Kotlin code directly in their browser, without needing to install any software. Kotlin compilers offer an integrated development environment (IDE) that includes features like syntax highlighting, error checking, code completion, and the ability to see the code output in real time.

About Kotlin 

Kotlin is a statically typed, cross-platform programming language developed by JetBrains. Introduced in 2011, it gained significant recognition when Google officially endorsed it as a preferred language for Android app development in 2017. Kotlin is designed to interoperate fully with Java, allowing seamless migration and use of existing libraries. Its succinct, expressive syntax aids in improving code readability and reducing boilerplate code. Kotlin also emphasizes safety, featuring built-in null safety to eliminate common null pointer errors. Its coroutines feature enables efficient handling of asynchronous programming and concurrency. Kotlin's usage extends beyond Android, being used for web, server-side, and desktop application development. With its modern design and robust features, Kotlin presents an appealing choice for developers.

Features of Online Kotlin Compiler

  • It can be accessed through any web browser
  • Easy to use interface and supports various libraries.
  • The syntax highlighting feature colours the elements of the code to increase readability.
  • Compiler’s Autocompletion feature accelerates coding by predicting already defined variables/functions and completing code.

Syntax Help

If-Else Statement:

In Kotlin, the syntax for the If-Else statement is similar to other languages like Java and C++. Here is how you can write an If-Else statement in Kotlin:


if (condition) {
           // block of code to be executed if the condition is true
           } else {
           // block of code to be executed if the condition is false


val a = 10
val b = 20

if (a > b) {
    println("$a is greater than $b")
} else {
    println("$a is less than $b")

Switch Statement:

Kotlin does not have a traditional "switch" statement as found in languages like Java or C++. Instead, it uses a more powerful construct called "when" that serves a similar purpose, but with enhanced capabilities.


val x = 3
val result = when (x) {
    1 -> "x is 1"
    2 -> "x is 2"
    else -> "x is neither 1 nor 2"
println(result) // prints "x is neither 1 nor 2"


val result = when (x) {
    1 -> "x is 1"
    2 -> "x is 2"
    else -> "x is neither 1 nor 2"
println(result) // prints "x is neither 1 nor 2"

For Loop: 

In Kotlin, the syntax for the For loop is a bit different than traditional For loops in languages like Java or C++


for (item in collection) {
    // block of code to be executed for each item in the collection


val numbers = arrayOf(1, 2, 3, 4, 5)
for (num in numbers) {

While Loop:

In Kotlin, the syntax for the While loop is similar to many other programming languages. The While loop executes a block of code as long as a particular condition is true.


while (condition) {
    // block of code to be executed as long as the condition is true


var i = 1
while (i <= 5) {

Do-While Loop: 

In Kotlin, the Do-While loop works similarly to the While loop, but with a key difference: the condition is evaluated after the execution of the block of code. This guarantees that the block of code gets executed at least once, regardless of the condition


do {
    // block of code to be executed
} while (condition)


var i = 1
do {
} while (i <= 5)

Functions in Kotlin

How to Declare Function

Functions in Kotlin are declared using the fun keyword:


fun functionName(parameter1: Type1, parameter2: Type2): ReturnType {
    // function body
    return value // value should be of ReturnType

How to call Function

You can call a function using its name followed by parentheses. If the function requires parameters, you provide them inside the parentheses. For example:


How to Define Function

A function is defined by specifying its name, parameters, return type, and body. Here's an example of a function that calculates the square of an integer:

fun square(number: Int): Int {
    return number * number

Working of the Online Kotlin Compiler (IDE)

An online Kotlin compiler, often called an Integrated Development Environment (IDE), is a tool that allows you to write, compile, and run Kotlin code directly in your web browser without having to install anything on your computer. This makes it an excellent choice for learning Kotlin, testing out small code snippets, or doing development work on machines where you can't or don't want to install a full development environment.

Here's how it typically works:

  • Writing Code: The online Kotlin compiler provides a text editor where you can write your Kotlin code. This editor often includes features like syntax highlighting, line numbers, and automatic indentation, making it easier to write and understand your code.
  • Compiling Code: Once you've written your code, you can compile it by clicking a button or using a keyboard shortcut. The compiler will check your code for syntax errors and other issues. If it finds any problems, it will display error messages to help you diagnose and fix them.
  • Running Code: If your code compiles successfully, you can run it in the online IDE. The output of your program will be displayed in a console window or similar area.
  • Sharing Code: Many online Kotlin compilers also allow you to share your code with others. This is great for collaborating with others, getting help with problems, or showing off your work.

One of the most popular online Kotlin compilers is the Kotlin Playground provided by JetBrains, the company that created Kotlin. It supports all of the above features and also includes options for running JavaScript or Java bytecode generated from your Kotlin code.

While an online Kotlin compiler can be a powerful tool, keep in mind that it may not support all the features of a full-fledged IDE like IntelliJ IDEA, such as debugging tools, advanced code refactoring, and integration with version control systems. However, for many tasks, an online Kotlin compiler is more than sufficient.

How to write and run the Kotlin program online

Writing and running a Kotlin program online is quite simple and straightforward. Here are the steps you can follow using the Kotlin Playground, an online Kotlin compiler provided by JetBrains:

Open the Kotlin Playground: Navigate to the Kotlin Playground in your web browser. 

Write Your Code: Once the Kotlin Playground is open, you will see a text editor area. Delete any existing code and start writing your own Kotlin program.

For example, you can write a simple program to print "Hello, World!" like this:

fun main() {
    println("Hello, World!")

Here, fun main() is the entry point of a Kotlin program, and println() is a function to print text to the console.

  • Run Your Code: After writing your code, click the green 'Run' button on the top-right of the page. This will compile and run your Kotlin program.
  • View the Output: After running your code, you can see the output of your program at the bottom of the page in the 'Output' section.
  • Debug and Iterate: If there are any errors in your program, they will be displayed in the 'Problems' tab next to 'Output'. You can use these error messages to debug and fix your code. After making changes, you can run your program again to see if the issues are resolved.
  • Save and Share: If you want to save your work or share it with others, you can click the 'Share' button. This will give you a unique URL that you can bookmark or send to others.

Remember, while the Kotlin Playground is a great tool for learning and experimenting, for more complex development tasks you might want to consider using a full-featured Integrated Development Environment (IDE) like IntelliJ IDEA.

Benefits of using Online Kotlin Compiler

Using an online Kotlin compiler offers several benefits:

  • No Installation Required: You don't need to install any software on your computer to use an online compiler. This can save time and effort, especially on systems where you don't have administrative privileges.
  • Platform Independence: Online compilers work in your web browser, so they can be used on any operating system including Windows, Mac, and Linux.
  • Easy to Share Code: Most online compilers provide an option to share your code with others. This can be useful for collaborative work, getting help with a problem, or showing off your work.
  • Perfect for Learning and Experimentation: If you're just learning Kotlin or want to try out a small piece of code, an online compiler is a quick and easy way to do it.
  • Automatic Updates: Online compilers are updated automatically, so you always have access to the latest features and bug fixes without having to update any software on your own machine.
  • Resource-Friendly: Since the compilation process takes place on the server, an online compiler can be a good choice for machines with limited resources.

Applications of Online Kotlin Compiler
Online Kotlin compilers can be used in a wide variety of scenarios:

  • Education and Learning: For students and self-learners, an online Kotlin compiler is an excellent tool for learning the language and practicing coding skills. It's also very useful for instructors who can share code snippets or complete programs with their students.
  • Quick Prototyping: For experienced developers, online compilers are a handy tool for quickly testing ideas or new language features, without the need to set up a local development environment.
  • Interviews and Assessments: Coding interviews and assessments can be conducted using online compilers. Candidates can write and run code during an interview, and interviewers can observe and evaluate their coding skills in real-time.
  • Collaboration: Online compilers often have features for sharing code, which is useful when collaborating with others. Team members can share a link to their code, making it easier to work together or get help with a problem.
  • Bug Reporting: When reporting a bug or asking a question on a forum or a site like StackOverflow, you can use an online Kotlin compiler to create a minimal, complete, and verifiable example. This makes it easier for others to understand the issue and provide help.
  • Serverless Execution: As the code runs on the server side, online compilers allow you to run Kotlin code even on devices where it might be impractical to install a full development environment, like tablets or Chromebooks.


  • Compiler: A compiler is an essential tool that can be used locally or online for compiling a code, that is, converting the code to a machine-based language for output.
  • Interpreter: An Interpreter is a tool that works similarly to a compiler, converting high-level code into machine-based language, but it converts the code line by line rather than in a single pass.
  • Online IDE: Online IDE, or Integrated Development Environment, is a software-based tool that is used as a single platform for all kinds of computer programming. It consists of an integrated compiler or interpreter, extensions, dependency files, and a debugger. Example: Eclipse
  • Code Editor: A Code Editor is another essential part of computer programming. It is a place where all source codes can be created and modified. It can be a stand-alone application or part of an IDE. Example: Vim and Sublime
  • Coding Ground: Coding Ground is a tool that provides easy accessibility to developers for using more than one programming language, technology, and framework. It allows developers to use various tools on a single platform.


This online Kotlin compiler is provided for educational and non-commercial use only. While Code 360 works diligently to make it accurate and user-friendly, we cannot guarantee error-free coding as challenges can occasionally arise with this tool. Code 360 is not responsible for any errors in the outcome based on the input by the user resulting from the use of this compiler.