Http4k: Server as a Function. In Kotlin. Typesafe. Without the Server

In plain words

Http4k is a Kotlin-based HTTP toolkit that enables developers to build and consume HTTP services using functional programming principles. It provides a lightweight, typesafe approach to handling HTTP requests and responses without requiring a traditional server framework. The toolkit is designed for Kotlin developers who prefer a functional, composable approach to HTTP service development, offering libraries for both serving and consuming HTTP services in a consistent manner.

written from the facts on this page · September 2026

From the sources

http4k is an HTTP toolkit written in Kotlin that enables the serving and consuming of HTTP services in a functional and consistent way. Whenever (yet another) new JVM HTTP framework is released, the inevitable question that rightly get asked is “How it this different to X?” . In this post, I’m going to briefly cover what http4k is, how we think it’s different, and address some of those bold claims from the title of this post. Firstly - we don’t consider http4k to be a framework - it’s a set of libraries providing a functional toolkit to serve and consume HTTP services, focusing on simple, consistent, and testable APIs. Hence, whilst it does provide…from http4k.org

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