Javalin - A Simple REST API Library for Java / Kotlin

Javalin is a very lightweight web framework for Kotlin and Java, inspired by Sparkjava and koa.js. Javalin is written in Kotlin with a few functional interfaces written in Java. This was necessary to provide an enjoyable and near identical experience for both Kotlin and Java developers.

• Lightweight - You don’t have to learn any advanced concepts to get started
• Consistent API - All handlers and mappers are void and operate on the Context (ctx)
• Almost identical API for both Kotlin and Java
• Not opinionated - A library rather than a framework (you never have to extend anything)
• Fully customizable embedded server (Jetty)
• JSON-object-mapping (via Jackson)
• Simple per-endpoint auth via AccessManager interface
• Simple static file handling
• Lifecycle events
• CookieStore - An easy way to serialize and store objects in cookies
• Template rendering (Velocity, Freemarker, Thymeleaf, Mustache)
• Markdown rendering