Javalin - A simple web framework for Java and Kotlin

Javalin is a very lightweight web framework for Kotlin and Java which supports WebSockets, HTTP2 and async requests. Javalin’s main goals are simplicity, a great developer experience, and first class interoperability between Kotlin and Java.

Javalin is more of a library than a framework. Some key points:

You don't need to extend anything
There are no @Annotations
There is no reflection
There is no other magic; just code.

General information:

❤️ Sponsor Javalin
The project webpage isjavalin.io (repo for webpage is atgithub.com/javalin/javalin.github.io).
Documentation:javalin.io/documentation
Chat on Discord:https://discord.gg/sgak4e5NKv
Chat on Slack:https://join.slack.com/t/javalin-io/shared_invite/zt-1hwdevskx-ftMobDhGxhW0I268B7Ub~w
Contributions are very welcome:CONTRIBUTING.md
License summary:https://tldrlegal.com/license/apache-license-2.0-(apache-2.0)
Interesting issues:/javalin/javalin/issues?q=label:INFO

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javalinjavalinPublic
A simple and modern Java and Kotlin web framework
Kotlin 8k 632
websitewebsitePublic
Javalin website source code
HTML 36 91
javalin-openapijavalin-openapiPublic
Annotation processor for compile-time OpenAPI & JsonSchema, with out-of-the-box support for Javalin 5.x & 6.x, Swagger & ReDoc
Kotlin 57 21
javalin-samplesjavalin-samplesPublic
Collection of many example projects for Javalin 4+
Kotlin 19 23

Showing 10 of 20 repositories

javalin Public
A simple and modern Java and Kotlin web framework
javalin/javalin’s past year of commit activity
Kotlin 8,036Apache-2.0 632 25 (2 issues need help) 9 UpdatedOct 1, 2025
javalin-openapi Public
Annotation processor for compile-time OpenAPI & JsonSchema, with out-of-the-box support for Javalin 5.x & 6.x, Swagger & ReDoc
javalin/javalin-openapi’s past year of commit activity
Kotlin 57Apache-2.0 21 13 (1 issue needs help) 1 UpdatedAug 30, 2025
website Public
Javalin website source code
javalin/website’s past year of commit activity
HTML 36 91 20 2 UpdatedJun 23, 2025
javalin-routing-extensions Public
Set of alternative routing implementations for Javalin 5.x & 6.x
javalin/javalin-routing-extensions’s past year of commit activity
Kotlin 17MIT 2 7 (1 issue needs help) 1 UpdatedJun 23, 2025
javalin-ssl Public
Straightforward SSL Configuration for Javalin!
javalin/javalin-ssl’s past year of commit activity
10 1 1 0 UpdatedMay 8, 2024
javalin-rendering Public
Artifact/module for server-side template/markdown rendering in Javalin:https://javalin.io/plugins/rendering
javalin/javalin-rendering’s past year of commit activity
Kotlin 12Apache-2.0 9 4 1 UpdatedMay 8, 2024
codeowner-selfmerge-action Public Forked fromOSS-Docs-Tools/code-owner-self-merge
Fork of a GitHub Action for letting CODEOWNERS merge PRs via green PR reviews
javalin/codeowner-selfmerge-action’s past year of commit activity
JavaScript 1MIT 16 0 1 UpdatedMay 6, 2024
javalin-samples Public
Collection of many example projects for Javalin 4+
javalin/javalin-samples’s past year of commit activity
Kotlin 19Apache-2.0 23 3 0 UpdatedMay 3, 2024
folder-ac-poc Public
javalin/folder-ac-poc’s past year of commit activity
Java 10 0 3 UpdatedFeb 19, 2024
kotlin-javalin-bazel-starter Public template Forked fromjorunfa/kotlin-javalin-bazel-starter
Starter template for Kotlin Javalin in Bazel
javalin/kotlin-javalin-bazel-starter’s past year of commit activity
Starlark 1Apache-2.0 2 0 0 UpdatedSep 19, 2023