Javalin – a simple web framework for Java and Kotlin

Unlike other Java and Kotlin web frameworks, Javalin has very few concepts that you need to learn. Javalin is just a few thousand lines of code on top of Jetty, and its performance is equivalent to raw Jetty code. Other Java and Kotlin web frameworks usually offer one version for each language. Javalin is being made with inter-operability in mind, apps are built the same way in both Java and Kotlin. Visit our educators page if you're teaching web programming and looking for a web framework which will get out of your way and let you focus on the core concepts of your curriculum. OpenAPI. Many lightweight Java and Kotlin web frameworks don't support OpenAPI, but Javalin does. Javalin runs on top of Jetty, one of the most used and stable web-servers on the JVM. You can configure the Jetty server fully, including SSL and HTTP3 and everything else that Jetty offers.