MUI Core: Ready-to-use foundational React components, free forever. It includes Material UI, which implements Google's Material Design.
Design patterns implemented in Java
Spring Boot
A utility-first CSS framework for rapid UI development.
Free and Open, Distributed, RESTful Search Engine
Everything you need to know to get the job.
Spring Framework
RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.