Introduction
Quickstart
About the docs
Concepts
Rationale HTTP Serverless WebSockets Server-Sent Events
Tutorials
Your first http4k app Deploying an http4k app to AWS Lambda Going native with Graal on AWS Lambda TDDing http4k
How-to guides
Overview Basic: Server as a function Basic: Client as a function Basic: Use a Server backend Basic: Different test-types Basic: Simple routing Basic: Nestable routes Attach context to a request Configure an OAuth Server Create a custom JSON marshaller Customise a Server backend Deploy WebJars Integrate with OpenAPI Leverage GraphQL Lookup a User Principal Monitor http4k Record & replay HTTP traffic Serve Server-Sent Events Serve Websockets Structure your logs with Events Test using Service Virtualisation Typesafe your API with lenses Secure and auth HTTP services Use a custom OAuth Provider Use a templating engine Use HTML forms Use Multipart forms Self document systems with tests Use Auto Content Negotiation Redoc and Swagger UI Make JSON Faster Make parallel HTTP calls
Reference
Overview Core Server backend Serverless backend HTTP & Websocket clients Typesafe contracts (OpenAPI3) JSON handling Templating Multipart forms Cloud Native Configuration Cloud Events Micrometer OpenTelemetry Resilience4J Failsafe AWS OAuth Digest GraphQL htmx Webhooks JSON RPC XML handling YAML handling Testing
Overview Approval Testing Chaos Testing Hamkrest Kotest Service Virtualisation Strikt Tracer Bullet WebDriver
Blog
Overview Meet http4k Typesafe Websockets Typesafe 12-factor config Documenting http4k apps with OpenApi3 Retrospective on v3 Nanoservices Toolbox: Guns for show, knives for a pro http4k v4 - 17 platforms and counting... http4k Platform v5 - New Servers, Loom, TracerBullet, OpenAI plugin SDK and more JCenter Shutdown
Changelog
http4k in action
Performance
FAQ
Getting support
Contribute/support http4k
Code of Conduct
Source Code

http4k in action

Media:¶

"Exploring the Testing Hyperpyramid with Kotlin & http4k" @ KotlinConf 2023 (video / slides / repo )
"Talking Kotlin ep. 99: HTTP as a function with http4k" (video / podcast)
"http4k: Server as a Function" (video), part of JetBrain's Webinar series
"Server as a Function. In Kotlin. ___" @ KotlinConf 2018 (video / slides), by David Denton and Ivan Sanchez
"Writing Test Driven Apps with http4k" (video), by David Denton and Ivan Sanchez, presented at Kotliners 2020.
"Designing Microservices in Functional Style" (video) by Uberto Barbini, presented at VirtualJUG 2020.
"Introduction to http4k" (video) by Dmitry Kandalov, based on previous conference talks, recorded in 2021.
"Test Driven Gilded Rose in Kotlin" (video series) by Duncan McGregor, recorded in 2021-22.

Also, check out the YouTube Playlist for the latest collection of talks featuring http4k.

See http4k in action in these example projects and repos:¶

There is a repository of helpful examples at http4k/examples, covering how to build http4k applications using various features.

Standalone projects...¶

Each project is tagged with the http4k features it demonstrates:

TDD'd example application ¶

Templates Testing JSON / Lenses CD pipeline Approval Testing OpenApi Static resources

Dropbox clone in 70 lines of Kotlin ¶

Templates Testing Http Client Multipart AWS CD pipeline Serverless GraalVM

Simple websocket driven chat-server in 30 lines of Kotlin ¶

Testing Websockets CD Pipeline Static resources

Stage-by-stage example of London-style TDD development process ¶

Testing

Todo backend (standard routing)¶

Testing JSON / Lenses CD pipeline

Todo backend (contract routing)¶

Testing JSON / Lenses OpenApi CD pipeline

Real World example (Medium clone)¶

Testing Contracts