.NET to Kotlin

Free .NET to Kotlin Code Converter

No email required. 100% free. Done in 30 seconds.

Transform your code from .NET to Kotlin with our free AI-based code convertion tool. If you like what you see, we also create documentation for your code! We don't ever store your code or any representation of it in our databases, but it will be shared with the LLM of our choice for processing.

Other tools






Ionic + Angular










React Native


Ruby on Rails






How to convert from .NET to Kotlin

Transitioning from .NET to Kotlin can be a challenging but rewarding task. Whether you are planning to migrate an existing application or start a new project in Kotlin, understanding the intricacies can help streamline the process. Below, you will find a comprehensive guide on how to convert from .NET to Kotlin, targeting proficient .NET developers who may be less familiar with Kotlin.

Understanding the Basics

.NET is a framework primarily used for building applications for Windows using languages like C# and VB.NET. Kotlin, on the other hand, is a statically-typed programming language developed by JetBrains, known for its efficiency in Android development but also applicable for backend development via JVM and Kotlin/Native.

Language Syntax Differences

The first step in converting your .NET code to Kotlin is to understand the syntax differences between the two languages.


public class Sample {
    public string Greet(string name) {
        return "Hello, " + name;


class Sample {
    fun greet(name: String): String {
        return "Hello, $name"

Notice how Kotlin simplifies class and method declarations. Kotlin uses fun for functions, and it avoids specifying the public access modifier by default.

Converting Data Types

Data types in Kotlin are somewhat similar but need attention for proper conversion.

.NET Kotlin
int Int
string String
float Float
double Double
bool Boolean

Handling Nullability

Kotlin has a unique approach to nullability which is stricter compared to .NET. In Kotlin, you must specify if a variable can hold a null value using a question mark.


string name = null;


var name: String? = null

Converting Control Flow Constructs

Both languages support similar control flow constructs like if-else, for loop, while loop, etc., but they differ in implementation.

For Loop in .NET:

for (int i = 0; i < 10; i++) {

For Loop in Kotlin:

for (i in 0..9) {

Exception Handling

Exception handling in both frameworks is quite similar.


try {
    // code that may throw an exception
} catch (Exception ex) {


try {
    // code that may throw an exception
} catch (ex: Exception) {

Converting Collections

Collections in Kotlin are more modern and come with rich APIs.

List in .NET:

List<string> names = new List<string>() { "John", "Jane", "Doe" };

List in Kotlin:

val names = listOf("John", "Jane", "Doe")

Common Libraries and Dependencies

When working with .NET, developers often utilize popular packages like Entity Framework for ORM, Newtonsoft.Json for JSON serialization, etc. In Kotlin, you might use libraries like Exposed for ORM and kotlinx.serialization for JSON parsing.

Example: Converting a Simple API Call

Let’s convert a simple API call from .NET to Kotlin.


using System.Net.Http;
using System.Threading.Tasks;

public async Task<string> FetchData(string url) {
    using HttpClient client = new HttpClient();
    HttpResponseMessage response = await client.GetAsync(url);
    string data = await response.Content.ReadAsStringAsync();
    return data;


import java.net.HttpURLConnection
import java.net.URL

suspend fun fetchData(url: String): String {
    val urlConnection = URL(url).openConnection() as HttpURLConnection
    return urlConnection.inputStream.bufferedReader().use {


While converting from .NET to Kotlin might initially seem daunting, understanding the fundamental differences in syntax, type system, control flow, error handling, and libraries can significantly ease the transition. This guide offers a streamlined path to help you achieve a smooth conversion, positioning you to leverage Kotlin's features effectively in your projects.

Document your code using AI

Sign up now
& free your developers' time

Start for free

Join thousands of companies documenting their code using AI.

Frequently Asked Questions

This free AI tool does its best to generate professional documentation. However, it's missing some context from other related files. The paid version takes into account different files to generate documentation for each use case, apart from the documentation of every file. You have also the possibility of add custom concepts to improve the knowledge of your codebase.

No. You don't have to enter any personal information to use Codex's free code documentation tool — it's 100% free.

No. An encrypted version of your code is stored only while its being processed and it's deleted immediately.

If you can work with a custom Azure model in your own account, let us know. If not, Codex also works with open source models that can run on-premises, on your own servers, so your data is always yours. Feel free to get in touch with us!