Top 10 Kotlin Frameworks for Web Development in 2024

Top 10 Kotlin Frameworks for Web Development

Kotlin has firmly established itself as a modern language for backend development. Thanks to full compatibility with Java, concise syntax, and a powerful type system, it has become the number one choice for many startups and enterprise projects. In this article, we have compiled the top 10 Kotlin frameworks for web development that will help you create fast, secure, and scalable web applications.

Why choose Kotlin for web development?

Before moving on to the list, let's highlight the key advantages of Kotlin:

• Compatibility with Java: you can use any Java libraries.
• Null-safety: fewer errors during runtime.
• Coroutines: asynchronous programming without callback hell.
• Conciseness: Kotlin code is on average 30% shorter than Java code.

1. Ktor — framework from JetBrains

Ktor is a modern asynchronous framework created specifically for Kotlin by JetBrains. It is ideal for microservices and REST APIs.

Key features:

• Fully asynchronous on coroutines.
• Modular architecture — connect only the components you need.
• Built-in support for WebSockets, HTTP/2, SSL.

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, Ktor!")            }        }    }.start(wait = true)}

2. Spring Boot — proven enterprise standard

Spring Boot remains the most popular framework for corporate development. Thanks to official Kotlin support, you can write in it as conveniently as in Java.

Advantages for Kotlin:

• Full support for coroutines via Reactor and WebFlux.
• Auto-configuration and a huge community.
• Ready-made starters for databases, security, queues.

Example of a controller on Spring Boot + Kotlin:

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

@RestController@RequestMapping("/api")class HelloController {

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

3. Javalin — lightweight and intuitive

Javalin is a minimalist web framework that is great for small projects and prototypes. It doesn't require a lot of code to get started.

Key features:

• Simple API, similar to Express.js.
• Built-in support for WebSockets, OpenAPI.
• Works on Java and Kotlin.

Example:

import io.javalin.Javalin

fun main() {    val app = Javalin.create().start(7000)    app.get("/") { ctx -> ctx.result("Hello, Javalin!") }}

4. http4k — functional and testable

http4k is a framework built on the principles of functional programming. It allows you to create HTTP applications as a composition of pure functions.

Features:

• Maximum testability (each component is a function).
• Support for multiple server engines (Netty, Jetty, Undertow).
• Built-in adapters for AWS Lambda, Serverless.

Example:

import org.http4k.core.*import org.http4k.server.*import org.http4k.routing.*

fun main() {    val app: HttpHandler = { request: Request ->        Response(Status.OK).body("Hello, http4k!")    }    app.asServer(Jetty(9000)).start()}

5. Vert.x —