Top Java Open‑Source Projects on GitHub in January

JavaGuide ( GitHub , ★22668) – A comprehensive Java learning and interview guide that covers the core knowledge most Java developers need.

advanced-java ( GitHub , ★7752) – An advanced‑level series covering topics such as MQ, Elasticsearch, Redis, Dubbo, Hystrix and more; recommended after basic introductions to each technology.

fescar ( GitHub , ★4476) – A high‑performance, easy‑to‑use Java‑based distributed transaction solution that enables fast commit and rollback of transactions.

mall ( GitHub , ★5603) – A full‑stack e‑commerce system built with Spring Boot and MyBatis, featuring a front‑end shop (home, product search, cart, order flow, etc.) and an extensive back‑office (product, order, member, promotion, analytics, finance, permissions, etc.).

miaosha ( GitHub , ★4379) – A high‑concurrency “flash‑sale” demo that demonstrates how to handle massive traffic using MQ, Spring Boot, Redis, Dubbo, Zookeeper, Maven, Lua, etc.

flink ( GitHub , ★7029) – Apache Flink is a declarative data‑analysis platform that combines the efficiency of distributed MapReduce‑style processing with flexible programming and extensibility, also offering query‑optimization for parallel databases.

cim ( GitHub , ★1797) – A developer‑focused instant‑messaging system (CROSS‑IM) providing scalable IM, message‑push middleware for apps, and transparent messaging for massive IoT connections.

Instant messaging system.

Message‑push middleware for mobile apps.

Transparent messaging for large‑scale IoT scenarios.

spring‑boot ( GitHub , ★33720) – A collection of libraries that simplify Spring application development, offering an embedded Tomcat, auto‑configuration, CLI, and production‑ready features such as metrics, health checks, and external configuration.

Create standalone Spring applications.

Embedded Tomcat, no WAR deployment.

Simplified Maven configuration.

Automatic Spring configuration.

Production‑ready features (metrics, health checks, external config).

No code generation, no mandatory XML.

symphony ( GitHub , ★10241) – A modern Java‑based community platform (forum/BBS/social network/blog) that supports content‑focused discussions, Q&A, and social features like sharing, friendships, and gaming.

arthas ( GitHub , ★9513) – A Java diagnostic tool that helps developers troubleshoot production issues without modifying code or restarting the JVM, enabling real‑time fault isolation.

tutorials ( GitHub , ★11255) – A collection of small, focused tutorials covering core Java, Jackson, HttpClient, Guava, and especially Spring Framework and Spring Security.