OpenAPI Plugin [](https://github.com/javalin/javalin-openapi/actions/workflows/gradle.yml) [](https://maven.reposilite.com/#/snapshots/io/javalin/community/openapi)

February 22, 2026 ยท View on GitHub

Compile-time OpenAPI integration for Javalin 7.x ecosystem. This is a new plugin that replaces old built-in OpenApi module, the API looks quite the same despite some minor changes.

Preview

How to use

See https://javalin.github.io/javalin-openapi.

Notes

  • Reflection free
  • Uses @OpenApi to simplify migration from bundled OpenApi implementation
  • Supports Java 17+ and Kotlin (through Kapt)
  • Uses internal WebJar handler that works with /* route out of the box
  • Provides better projection of OpenAPI specification
  • Schema validation through Swagger core module

Other examples

  • Test module - JavalinTest shows how this plugin work in Java codebase using various features
  • Reposilite - real world app using Javalin and OpenApi integration

Repository structure

Universal modules

ModuleDescription
openapi-annotation-processorCompile-time annotation processor, should generate /openapi-plugin/openapi-{default/<version>}.json resources
openapi-generatorShared schema generation logic: type mappings, runtime builder DSL, example generation
openapi-specificationAnnotations & classes used to describe OpenAPI specification
examplesExample Javalin application that uses OpenApi plugin in Gradle & Maven

Javalin plugins

PluginDescription
javalin-openapi-pluginLoads /openapi-plugin/openapi-{default/<version>}.json resources and serves main OpenApi endpoint
javalin-swagger-pluginServes Swagger UI
javalin-redoc-pluginServes ReDoc UI

Branches

BranchJavalin versionOpenApi VersionJava Version
main7.x7.xJDK17
6.x6.x6.xJDK11
5.x5.x5.xJDK11
4.x4.x1.xJDK8