Top 12 Must‑Watch Java Open‑Source Projects on GitHub (May)

1. shenyu

https://github.com/dromara/shenyu – Star 4664. An extensible, high‑performance, reactive API gateway solution applicable to all microservice scenarios.

2. java-design-patterns

https://github.com/iluwatar/java-design-patterns – Star 67279. A comprehensive handbook of design patterns for Java developers, offering best‑practice solutions to common software design problems and helping accelerate development while avoiding critical mistakes.

3. pulsar

https://github.com/apache/pulsar – Star 8707. Apache Pulsar is a top‑level Apache project delivering a next‑generation cloud‑native distributed messaging platform that integrates messaging, storage, and lightweight function computing, originally developed at Yahoo and now handling billions of messages daily.

4. leetcode

https://github.com/doocs/leetcode – Star 5298. A repository containing solutions to LeetCode, "剑指 Offer (2nd edition)", and "程序员面试金典 (6th edition)" problems in multiple languages such as Java, Python, C++, JavaScript, C#, and Go, updated regularly.

5. airbyte

https://github.com/airbytehq/airbyte – Star 2942. An open‑source data integration platform that synchronizes data from applications, APIs, and databases to warehouses, making data pipelines simple, secure, and scalable.

6. APIJSON

https://github.com/Tencent/APIJSON – Star 10972. A JSON‑based network transmission protocol and ORM library designed for APIs, providing fully automated CRUD, complex queries, and transaction support to dramatically reduce development and communication costs.

7. TheAlgorithms/Java

https://github.com/TheAlgorithms/Java – Star 37797. A complete collection of algorithms implemented in Java, covering a wide range of computer‑science topics.

8. (Unnamed)

https://github.com/981011512/-- – Star 3147. A complete parking‑lot management system built with Java, Spring Boot, OAuth2, MySQL/MongoDB/Redis, Netty, native Android/iOS clients, Vue‑TypeScript admin template, and FastDFS file service.

9. SpringAll

https://github.com/wuyouzhuguli/SpringAll – Star 20443. Source code for a personal blog covering Spring Boot, Spring Boot & Shiro, Spring Cloud, and Spring Security & OAuth2 implementations.

10. JimuReport

https://github.com/zhangdaiscott/JimuReport – Star 2000. A free data‑visualization tool for designing reports and dashboards with an Excel‑like drag‑and‑drop interface, supporting report design, charting, printing, and large‑screen displays.

11. java-tron

https://github.com/tronprotocol/java-tron – Star 2689. The Java implementation of the TRON protocol, aiming to build infrastructure for a truly decentralized internet.

12. keycloak

https://github.com/keycloak/keycloak – Star 8981. An open‑source identity and access management solution that secures applications and services through simple configuration.