Top 10 Kotlin Frameworks for Web Development — Part 3

We continue our journey through the world of web development with Kotlin. If you are already familiar with the basics of programming in this language and are looking for learning new tools, this article is for you. In the third part, we will look at several more powerful frameworks that will help you create modern web applications. The material will be useful both for Kotlin for beginners and for experienced developers.

1. Ktor — Lightweight and Asynchronous

Ktor is a framework from JetBrains, created specifically for Kotlin. It is fully asynchronous and supports both server and client sides. Ktor is ideal for microservices and REST APIs.

Example of a Simple Server on Ktor

import io.ktor.server.engine.*import io.ktor.server.netty.*import io.ktor.server.routing.*import io.ktor.server.response.*

fun main() {    embeddedServer(Netty, port = 8080) {        routing {            get("/") {                call.respondText("Hello, world! This is Ktor")            }        }    }.start(wait = true)}

Ktor is great for learning Kotlin for beginners, as its code is concise and clear. The framework is actively developed and supported by the community.

2. Spring Boot with Kotlin — The Power of Spring for Kotlin

Spring Boot is one of the most popular frameworks for web programming in Java. Thanks to full support for Kotlin, you can use all the features of Spring while retaining the advantages of the Kotlin language: null safety, extension functions, and coroutines.

Example of a Controller on Spring Boot + Kotlin

import org.springframework.web.bind.annotation.*

@RestControllerclass HelloController {

    @GetMapping("/hello")    fun hello(@RequestParam name: String): String {        return "Hello, $name!"    }}

Spring Boot is an excellent choice for enterprise projects and scalable applications. If you are taking learning courses on Spring, then Kotlin will make your code cleaner and safer.

3. Javalin — Simple and Elegant

Javalin is a lightweight web framework for Kotlin and Java. It is inspired by Ktor but offers a simpler API. Javalin is ideal for small projects and prototypes.

Example of a Route in Javalin

import io.javalin.Javalin

fun main() {    val app = Javalin.create { config ->        config.enableCorsForAllOrigins()    }.start(7070)

    app.get("/") { ctx ->        ctx.result("Javalin is working!")    }}

Javalin is great for Kotlin for beginners, as it does not require complex configuration. You can start writing code immediately after adding the dependency.

4. Vert.x — Reactive and Multithreaded

Vert.x is a toolkit for building reactive applications on the JVM. It supports Kotlin out of the box and offers an event-driven architecture. Vert.x is ideal for high-load systems and real-time applications.

Example of Vert.x with Kotlin

import io.vertx.kotlin.core.*import io.vertx.core.Vertx

fun main() {    val vertx = Vertx.vertx()    vertx.createHttpServer().requestHandler { req ->        req.response()            .putHeader("content-type", "text/plain")            .end("Hello from Vert.x!")    }.listen(8888)}

Vert.x requires some understanding of reactive programming, but thanks to Kotlin, the code remains readable. This is an excellent choice for those who want to delve into asynchronous development.

Conclusion

We have looked at four frameworks from our top ten: Ktor, Spring Boot, Javalin, and Vert.x. Each of them is suitable for different tasks:

• Ktor — for microse