vaadin

Vaadin is an open-source web application framework for Java that enables developers to build modern, interactive web UIs without writing extensive JavaScript. It provides a rich set of reusable UI components and a programming model in which most UI logic runs on the server, while the client renders components as end-user interfaces.

Vaadin's architecture centers on Flow, a Java API for building UIs. When a user interacts with a component, events are sent to the server over a bidirectional connection (WebSocket or long-polling), the server updates the component state, and Vaadin pushes DOM changes back to the client. This server-driven approach reduces JavaScript boilerplate for common tasks such as routing, layout, data binding, and form validation. The client side uses lightweight web components to render the UI.

History and scope: Founded in 2002 as Vaadin Framework; transitioned in 2019-2020 to the Vaadin Platform with Flow (server-side Java) and Fusion (client-side TypeScript). Vaadin 10+ introduced a new architecture and an open-source core with enterprise offerings; current versions in the 24.x series emphasize Spring Boot and modern Java development.

Components and tooling: Vaadin includes components like Grid, FormLayout, ComboBox, TreeGrid, Charts; theming via CSS, Material or Lumo design; Vaadin Designer for visual UI design; Vaadin Directory for add-ons; integrates with Maven, Gradle, and Spring Boot.

Licensing and ecosystem: The core platform is open source (Apache 2.0 license); additional professional support and commercial add-ons are offered by Vaadin Ltd. The ecosystem includes Vaadin Flow for Java, Vaadin Fusion for TypeScript-based development, and Platform tooling.

Usage: Commonly used for enterprise applications, internal tools, dashboards; suits teams comfortable with Java and Spring Boot; suitable for rapid development with a single language across the stack.