fritz2

easily building reactive web-apps in pure Kotlin

fun main() {
    val store = storeOf("")
    render("#target") {
        div {
            div("form-group") {
                label {
                    `for`(store.id)
                    +"Input"
                }
                input("form-control", id = store.id) {
                    placeholder("Add some input")
                    value(store.data)
                    changes.values() handledBy store.update
                }
            }
            div("form-group") {
                label { +"Value" }
                div("form-control") {
                    store.data.asText()
                    attr("readonly", "true")
                }
            }
            div("form-group") {
                button("btn btn-primary") {
                    +"Add a dot"
                    clicks handledBy store.handle { "$it." }
                }
            }
        }
    }
}

Lightweight, reactive, easy to learn

fritz2 heavily uses Kotlin standard features (especially flows) and has no external dependencies. It's core source is just about 1,5k lines of code so it is one of the most lightweight ui-libs (we know...).

fritz2 offers precise data-binding for your ui-elements. When your data changes, those - and only those - DOM-elements are updated, that are bound to parts of the model, that really have changed - no virtual dom needed.

fritz2 is built around just a few basic concepts (Stores, Handlers, Tags, etc.). You can easily learn how to use them from our documentation or the examples we provide. Enjoy!

Flexible, effective, ready to go

fritz2 allows you to build small apps very fast with a few lines of code as well as enterprise scale applications with a focus on reusable components, clean code and structure. The functional reactive concept makes the resulting code easy to read and to maintain.

fritz2 includes everything you need to start your project: state management (even for complex nested models), validation, routing, REST, WebSockets, WebComponents as well as a set of tailor-made components.

Utilizing Koltin's multiplatform-abilities, you have to write your data classes and validation code (!) just once and use it in your client and server. Use a tool-chain (Gradle, IDEA, etc.) you know well to jump right in and build your apps.

percent pure Kotlin

external dependencies

lines of code in the core