It lets you build full web UIs without touching HTML, CSS, or JavaScript, entirely in Java. The UI logic runs on the server, meaning: no API design, no JSON mapping, no Redux — just a Java object model.
Vaadin follows a true full-stack approach, where frontend and backend live in a single codebase. Combined with Spring Boot or other JVM frameworks, this creates a cohesive Java application—no complex build pipelines, no split repos, and no friction between frontend/backend roles.
What I personally enjoy most is the smooth developer experience: you see your changes reflected in the browser instantly — no manual builds, reload fiddling, or sluggish toolchains - just java and a bit of maven. For many internal business apps, it feels just as “plain” as the old-school server-rendered apps—just with modern capabilities like Web Components and security by default.
(Full disclosure: I work at Vaadin, but I’m genuinely a fan of the approach because it saves developers a lot of headaches.)