# Javalin

> Javalin is a lightweight web framework for Java and Kotlin. Version 7 (current) requires Java 17+ and runs on Jetty 12. All configuration — routes, handlers, plugins, lifecycle events — is passed upfront in a single config block when creating the instance.

Key facts for v7:
- Minimum Java version is 17 (was 11 in v6)
- Built on Jetty 12 (was Jetty 11 in v6)
- All setup is done inside `Javalin.create(config -> { ... })` — routes and handlers are no longer added after `.start()`
- Template engine support is now modular: add `javalin-rendering-{engine}` instead of a monolithic `javalin-rendering` artifact
- Kotlin support targets Kotlin 2.0

## Docs

- [Documentation](https://javalin.io/documentation): Full v7 reference — routing, handlers, WebSockets, validation, access management, SSE, configuration, lifecycle, plugins
- [Migration guide: v6 → v7](https://javalin.io/migration-guide-javalin-6-to-7): Required reading for anyone upgrading from v6; covers all breaking changes including the upfront-config model, Jetty 12, and Java 17 minimum

## Plugins

- [CORS plugin](https://javalin.io/plugins/cors): Configure CORS policies; replaces the old `app.enableCors()` API
- [OpenAPI plugin](https://javalin.io/plugins/openapi): Generate OpenAPI/Swagger documentation from annotated route handlers
- [Rendering plugin](https://javalin.io/plugins/rendering): Template engine support (Freemarker, Thymeleaf, Mustache, Velocity, Pebble, JTE, Handlebars, CommonMark) via per-engine `javalin-rendering-{engine}` modules
- [JavalinVue plugin](https://javalin.io/plugins/javalinvue): Server-driven Vue.js component loading without a build step
- [SSL plugin](https://javalin.io/plugins/ssl-helpers): HTTPS/HTTP2/mTLS configuration helper
- [GraphQL plugin](https://javalin.io/plugins/graphql): Add a GraphQL endpoint
- [Micrometer plugin](https://javalin.io/plugins/micrometer): Expose Micrometer metrics
- [Route overview plugin](https://javalin.io/plugins/routeoverview): Expose a JSON overview of all registered routes
- [Dev logging plugin](https://javalin.io/plugins/devlogging): Pretty-print incoming requests and responses during development
- [How to create plugins](https://javalin.io/plugins/how-to): Guide for writing custom Javalin plugins

## Optional

- [Archived v6 docs](https://javalin.io/archive/docs/v6.X.html): Full reference for Javalin 6 (Java 11+, Jetty 11)
- [Archived v5 docs](https://javalin.io/archive/docs/v5.6.X.html): Full reference for Javalin 5