Top JAVA GitHub Repositories & Tools (2026)

Java SDK for building Kubernetes Operators

Beanshell scripting language

Apache CXF

An Intuitive Event-Driven Reactive Programming Library for Java

Eclipse Ditto™: Digital Twin framework of Eclipse IoT - main repository

Virtual Tabletop for playing roleplaying games with remote players or face to face.

Helios server

Batteries-included backend that works with any stack.

Mirror of Apache MINA

The Stack Overflow clone for your team (self-hosted or hosted)

Lucee is a high-performance, open-source CFML server written in Java. Supporting JDBC, Caching, Parallelism, HTTP, ORM, REST, S3 and dynamic Java integration, Lucee is great for developers aiming to build fast, scalable applications, delivering faster startup, rapid compilation and better runtime performance.

A modern, lambda-friendly, 120 character Java formatter.

Use Apache Causeway™ to rapidly develop domain-driven apps or modular monoliths in Java, on top of the Spring Boot platform. Write your business logic in entities, domain services or view models, and the framework dynamically generates a representation of that domain model as a webapp, GraphQL or RESTful API. For prototyping or production.

A plugin for generating BuildConstants for any kind of Gradle projects: Java, Kotlin, Groovy, etc. Designed for KTS scripts.

A modern SCORM JavaScript runtime library.

The ultra-versatile RPG skills plugin

Mobile-first web interface for OpenCode AI agents. Manage, control, and code with multiple OpenCode agents from any device - your phone, tablet, or desktop. Features Git integration, file management, and real-time chat in a responsive PWA. Deploy with Docker for instant setup.

True Object-Oriented Java Web Framework without NULLs, Static Methods, Annotations, and Mutable Objects

Confidential Consortium Framework

A Java library for parsing and building iCalendar data models