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Top 23 Java Open-Source Projects
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Project mention: JavaGuide: Comprehensive Java Learning and Interview Prep Resource | news.ycombinator.com | 2024-08-15
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InfluxDB
InfluxDB high-performance time series database. Collect, organize, and act on massive volumes of high-resolution data to power real-time intelligent systems.
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Java Design Patterns GitHub Repo
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advanced-java
😮 Core Interview Questions & Answers For Experienced Java(Backend) Developers | 互联网 Java 工程师进阶知识完全扫盲：涵盖高并发、分布式、高可用、微服务、海量数据处理等领域知识
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Spring Boot
Spring Boot helps you to create Spring-powered, production-grade applications and services with absolute minimum fuss.
Project mention: Spring Boot and Java 24: What Developers Need to Know in 2025 | dev.to | 2025-04-17When building native images, especially with Netty, upgrade GraalVM reachability metadata manually to version 0.3.14 for full compatibility (Spring Boot 3.4 Release Notes).
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ElasticSearch Loses Stars
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CodeRabbit
CodeRabbit: AI Code Reviews for Developers. Revolutionize your code reviews with AI. CodeRabbit offers PR summaries, code walkthroughs, 1-click suggestions, and AST-based analysis. Boost productivity and code quality across all major languages with each PR.
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Stirling-PDF
#1 Locally hosted web application that allows you to perform various operations on PDF files
Project mention: A free, unlimited online PDF converter with Privacy focus | news.ycombinator.com | 2025-01-03Congrats on the launch, it is interesting. Do you have plans for open source the project?
I'm a happy user of Stirling-PDF [1] which provides all my PDF needs. I do host it in my network and not accessible from internet for better privacy.
[1] https://github.com/Stirling-Tools/Stirling-PDF
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leetcode-master
《代码随想录》LeetCode 刷题攻略：200道经典题目刷题顺序，共60w字的详细图解，视频难点剖析，50余张思维导图，支持C++，Java，Python，Go，JavaScript等多语言版本，从此算法学习不再迷茫！🔥🔥 来看看，你会发现相见恨晚！🚀
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leetcode
LeetCode Solutions: A Record of My Problem Solving Journey.( leetcode题解，记录自己的leetcode解题之路。) (by azl397985856)
1️⃣3️⃣ LeetCode Solutions 🏆 📌 https://github.com/azl397985856/leetcode A collection of LeetCode solutions to prepare for FAANG interviews.
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RxJava
RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.
Project mention: Why Ruby's Timeout is dangerous (and Thread.raise is terrifying) (2015) | news.ycombinator.com | 2024-06-03 -
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Project mention: Energy-Efficient Schema-Driven Development with Spring WebMVC/WebFlux | dev.to | 2025-04-20
At first, I thought it was just a knockoff of Retrofit (sorry...), but it turns out you can also use it as a controller interface. The *Exchange annotations in the earlier example come from this HTTP Interface.
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JeecgBoot
🔥一款基于AIGC和低代码引擎的AI低代码平台，旨在帮助企业快速实现低代码开发和构建、部署个性化的 AI 应用。 前后端分离 SpringBoot，SpringCloud，Ant Design&Vue3，Mybatis，Shiro！强大的代码生成器让前后端代码一键生成，无需写任何代码! 成套AI大模型功能: AI模型管理、AI应用、知识库、AI流程编排、AI对话助手等；
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Project mention: How to Reduce Big Data Analytics Costs by 90% with Karpenter and Spark | dev.to | 2025-04-21
Apache Spark powers large-scale data analytics and machine learning, but as workloads grow exponentially, traditional static resource allocation leads to 30–50% resource waste due to idle Executors and suboptimal instance selection.
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Let's look at the example from Apache Dubbo:
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MPAndroidChart
A powerful 🚀 Android chart view / graph view library, supporting line- bar- pie- radar- bubble- and candlestick charts as well as scaling, panning and animations.
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appsmith
Platform to build admin panels, internal tools, and dashboards. Integrates with 25+ databases and any API.
Project mention: Top 40 Open-source Developer Tools with the Most GitHub Stars | dev.to | 2025-04-20 -
Ray
Ray is an AI compute engine. Ray consists of a core distributed runtime and a set of AI Libraries for accelerating ML workloads.
I'm guessing this comment is some kind of "if you know, you know." Likely starting from https://docs.ray.io/en/latest/cluster/vms/user-guides/launch... and then trawling through one of these I guess https://github.com/ray-project/ray/issues?q=is%3Aissue+prem+...
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SaaSHub
SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives
NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
Java discussion
Java related posts
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Energy-Efficient Schema-Driven Development with Spring WebMVC/WebFlux
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Growing a Language, by Guy Steele [pdf]
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Show HN: UML diagram for the DDD example in Evans' book
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How to Dump Database Tables into Files to Speed Up Queries with EsProc
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Working on the Open Data Editor at the Open Knowledge Foundation
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Spring Boot and Java 24: What Developers Need to Know in 2025
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SAST vs SCA: Choosing the Right Source Code Security Scanning Tools
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A note from our sponsor - SaaSHub
www.saashub.com | 21 Apr 2025
Index
What are some of the best open-source Java projects? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | JavaGuide | 149,268 |
| 2 | Design Patterns | 91,314 |
| 3 | advanced-java | 77,469 |
| 4 | Spring Boot | 76,830 |
| 5 | Elasticsearch | 72,407 |
| 6 | interviews | 64,080 |
| 7 | Java | 61,343 |
| 8 | Stirling-PDF | 55,943 |
| 9 | leetcode-master | 55,565 |
| 10 | leetcode | 55,253 |
| 11 | Guava | 50,678 |
| 12 | RxJava | 48,080 |
| 13 | OkHttp | 46,296 |
| 14 | jadx | 43,622 |
| 15 | Retrofit | 43,436 |
| 16 | dbeaver | 43,114 |
| 17 | JeecgBoot | 42,330 |
| 18 | Apache Spark | 40,958 |
| 19 | Dubbo | 40,904 |
| 20 | MPAndroidChart | 37,923 |
| 21 | appsmith | 36,678 |
| 22 | Ray | 36,619 |
| 23 | Arthas | 36,168 |
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