Glimmer - Fast and light-weight UI components for the web
Vaadin Framework - Vaadin is a web application framework for Rich Internet Applications (RIA).
Svelte - Cybernetically enhanced web apps
jHipster - JHipster is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures.
Preact.js - Preact is a fast 3kB alternative to React with the same modern API. Components & Virtual DOM.
Grails - An Open Source, full stack, web application framework for the JVM