101 open source projects written in Java
Every Java project in the registry, ranked by GitHub stars — license and last push on every entry, data pulled live from the GitHub API every night.
mall ★ 85K mall项目是一套电商系统，包括前台商城系统及后台管理系统，基于Spring Boot+MyBatis实现，采用Docker容器化部署。 前台商城系统包含首页门户、商品推荐、商品搜索、商品展示、购物车、订单流程、会员中心、客户服务、帮助中心等模块。 后台管理系统包含商品管理、订单管理、会员管理、促销管理、运营管理、内容
Elasticsearch ★ 78K The leading distributed search and analytics engine
DBeaver ★ 52K Free database manager for SQL databases and beyond
JeecgBoot ★ 48K 【低代码v2.0，一句话即可生成整个系统】企业级AI低代码平台，一键生成前后端代码甚至整个系统。 AI Skills 一句话画流程、设计表单、生成报表、大屏。内置 AI应用平台涵盖：AI聊天、知识库、流程编排、MCP插件等，兼容主流大模型。引领AI低代码「Skills 生成 → 在线配置 → 代码生成 → 手工合并->
halo ★ 40K Halo 是一款强大易用的开源建站工具，从个人博客、知识库，到企业官网、在线商城，Halo 都能助您轻松实现，一站式满足您的多样化建站需求。
Keycloak ★ 37K Secure authentication and access control made simple
conductor ★ 32K Conductor is an event driven agentic workflow engine providing durable and highly resilient execution engine for applications and AI Agents
xxl-job ★ 31K A distributed task scheduling framework.（分布式任务调度平台XXL-JOB）
Kestra ★ 28K Declarative workflow orchestration for data, AI, and infra
Chat2DB ★ 28K Transform natural language into SQL queries with AI
openapi-generator ★ 27K OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec
jenkins ★ 27K Jenkins automation server
Apache SkyWalking ★ 25K Distributed tracing, metrics, logs, and GenAI monitoring in one
floci ★ 25K Light, fluffy, and always free - The AWS Local Emulator alternative
dataease ★ 24K 🔥 人人可用的开源 BI 工具，数据可视化神器。An open-source BI tool alternative to Tableau.
redisson ★ 24K Redisson: Valkey & Redis Java Client and Real-Time Data Platform. Sync/Async/RxJava/Reactive API. Over 50 Valkey and Redis based Java objects and services: Set,
shardingsphere ★ 21K Empowering Data Intelligence with Distributed SQL for Sharding, Scalability, and Security Across All Databases.
DoKit ★ 20K 一款面向泛前端产品研发全生命周期的效率平台。
zipkin ★ 17K Zipkin is a distributed tracing system
QuestDB ★ 17K High-performance time-series database for massive data scale
neo4j ★ 17K Graphs for Everyone
doris ★ 16K Apache Doris is a real-time analytics and hybrid search database for AI agents.
SuperTokens ★ 15K Secure, customizable authentication for your applications
onedev ★ 15K The Unified and Autonomous Development Platform
LanguageTool ★ 15K AI-powered grammar checker for 30+ languages
Logstash ★ 15K Centralize, transform, and stash your data
dolphinscheduler ★ 14K Apache DolphinScheduler is the modern data orchestration platform. Agile to create high performance workflow with low-code
Apache Druid ★ 14K Real-time analytics database for sub-second OLAP queries
pinpoint ★ 14K APM, (Application Performance Management) tool for large-scale distributed systems.
OpenSearch ★ 14K Open-source search and analytics at enterprise scale
trino ★ 13K Official repository of Trino, the distributed SQL query engine for big data, formerly known as PrestoSQL (https://trino.io)
debezium ★ 13K Change data capture for a variety of databases. Please log issues at https://github.com/debezium/dbz/issues.
langchain4j ★ 13K LangChain4j is an idiomatic, open-source Java library for building LLM-powered applications on the JVM. It offers a unified API over popular LLM providers and v
Aegis Authenticator ★ 13K 2FA token manager for Android with encrypted vault
starrocks ★ 12K The world's fastest open query engine for sub-second analytics both on and off the data lakehouse. With the flexibility to support nearly any scenario, StarRock
webmagic ★ 12K A scalable web crawler framework for Java.
jsoup ★ 11K jsoup: the Java HTML parser, built for HTML editing, cleaning, scraping, and XSS safety.
AutoMQ ★ 11K S3-based serverless Kafka reinvented for cost efficiency
resilience4j ★ 11K Resilience4j is a fault tolerance library designed for Java8 and functional programming
seatunnel ★ 9.7K SeaTunnel is a multimodal, high-performance, distributed, massive data integration tool.
flowable-engine ★ 9.5K A compact and highly efficient workflow and Business Process Management (BPM) platform for developers, system admins and business users.
astron-agent ★ 9.0K Enterprise-grade, commercial-friendly agentic workflow platform for building next-generation SuperAgents.
karate ★ 9.0K Test Automation Made Simple
shenyu ★ 8.8K Apache ShenYu is a Java native API Gateway for service proxy, protocol conversion and API governance.
transmittable-thread-local ★ 8.3K 📌 a missing Java std lib(simple & 0-dependency) for framework/middleware, provide an enhanced InheritableThreadLocal that transmits values between threads even
so-novel ★ 8.1K 小说下载｜网文下载 | 网络小说
DependencyCheck ★ 7.7K OWASP dependency-check is a software composition analysis utility that detects publicly disclosed vulnerabilities in application dependencies.
swagger-core ★ 7.5K Examples and server integrations for generating the Swagger API Specification, which enables easy access to your REST API
gocd ★ 7.4K GoCD - Continuous Delivery server main repository
hertzbeat ★ 7.4K An AI-powered next-generation open source real-time observability system.
wiremock ★ 7.4K A tool for mocking HTTP services
flink-cdc ★ 6.5K Flink CDC is a streaming data integration tool
Apache IoTDB ★ 6.4K Time-series database built for industrial IoT workloads
Apache Pinot ★ 6.1K Distributed OLAP database for real-time analytics at scale
OSMAnd ★ 6.0K Navigate anywhere with detailed offline maps and GPS
btrace ★ 6.0K Production-safe dynamic tracing and diagnostics for Java applications—attach to live JVMs with no restart or recompilation.
Infinity-For-Reddit ★ 5.5K A Reddit client for Android
orientdb ★ 5.0K OrientDB is the most versatile DBMS supporting Graph, Document, Reactive, Full-Text and Geospatial models in one Multi-Model product. OrientDB can run distribut
mockserver-monorepo ★ 5.0K MockServer is an HTTP(S) mock server and proxy for testing that lets you mock APIs, inspect and modify live traffic, and inject failures. It supports HTTP/1.1,
spring-cloud-gateway ★ 4.9K An API Gateway built on Spring Framework and Spring Boot providing routing and more.
CrateDB ★ 4.4K Scalable SQL database for real-time analytics
grimmory ★ 4.4K A self-hosted library for your ebooks, comics, and audiobooks
freeplane ★ 4.4K Application for Mind Mapping, Knowledge Management, Project Management. Develop, organize and communicate your ideas and knowledge in the most effective way.
chunjun ★ 4.1K A data integration framework
kubernetes-client ★ 3.7K Java client for Kubernetes & OpenShift
proguard ★ 3.7K ProGuard, Java optimizer and obfuscator
hugegraph ★ 3.2K A graph database that supports more than 100+ billion data, high performance and scalability (Include OLTP Engine & REST-API & Backends)
Openfire ★ 3.1K An XMPP server licensed under the Open Source Apache License.
symphony ★ 2.9K 🎶 一款用 Java 实现的现代化社区（论坛/问答/BBS/社交网络/博客）系统平台。A modern community (forum/Q&A/BBS/SNS/blog) system platform implemented in Java. https://ld246.com
RedReader ★ 2.7K An unofficial open source Android app for Reddit.
UniversalMediaServer ★ 2.7K A DLNA, UPnP and HTTP(S) Media Server.
Peergos ★ 2.5K Secure, private, and decentralized file storage
Saturn ★ 2.3K The vip.com's distributed job scheduling platform.
tinkerpop ★ 2.1K Apache TinkerPop - a graph computing framework
microcks ★ 2.0K The open source, cloud native tool for API Mocking and Testing. Microcks is a Cloud Native Computing Foundation incubating project 🚀
yas ★ 2.0K YAS: Yet Another Shop, a sample microservices project in Java
oms-erp ★ 1.9K 一站式全渠道业务中台系统包括订单管理系统OMS/电商ERP、库存WMS统一管理系统和SAP财务管理系统等，实现快速部署，并帮助企业后续自主进行开发迭代，实现数字化转型，并有多个经典案例。中台系统包括：通用业务中台、强大的技术中台Springcloud/Istio、后续开发方案的设计，技术(K8S,SERVERLESS)
kairosdb ★ 1.8K Fast scalable time series database
akto ★ 1.5K Akto is the fastest growing AI Security platform for your teams to secure AI agents, MCPs, LLMs, Agent skills, Gen AI apps in your organization.
MaterialAbout ★ 1.5K 🔖 It's a material-design about screen to use on your Android apps. A developer profile and application information easy to integrate.
hop ★ 1.5K Hop Orchestration Platform
Addax ★ 1.4K Actively maintained fork of Alibaba DataX — a fast, versatile ETL tool for RDBMS/NoSQL data transfer
jasperreports ★ 1.4K JasperReports® - Free Java Reporting Library
XWiki ★ 1.3K Open-source knowledge management and collaboration platform
rebuild ★ 1.1K 最新版全面支持AI智能！通过自然语言操作业务数据，支持 Skills/工具/知识库/MCP。高度可配置化的国产企业管理系统，企业内部可免费商用！零代码/低代码快速搭建WMS库存管理、MES生产报工、CRM客户管理、HRM人事管理，以及 TMS/ERP 等
zerocode ★ 1.0K zerocode-tdd is a community-developed, free, open-source, outcome-driven automated testing framework for Data Pipelines, ETL, REST API, Kafka(Data Streams), Dat
ByteChef ★ 1.0K Build AI agents and automate complex workflows seamlessly
scoold ★ 923 The Stack Overflow clone for your team (self-hosted or hosted)
seatunnel-web ★ 880 SeaTunnel is a distributed, high-performance data integration platform for the synchronization and transformation of massive data (offline & real-time).
WorkFlow-Engine ★ 865 工作流引擎对内提供单位/机关流程管理规则和内部业务流程的数字化落地实践；对外提供自动化地第三方业务驱动、接口接入和算法单元驱动能力。工作流引擎在提供底层驱动引擎的同时对全局透明监控、安全防御和国产化特色功能进行充分考虑，是内部流程管理和业务算法驱动的不二之选。
ical4j ★ 837 A Java library for parsing and building iCalendar data models
Structr ★ 830 Build complete web apps with integrated graph database
davmail ★ 758 DavMail POP/IMAP/SMTP/CalDAV/CardDAV/LDAP Exchange and Office 365 Gateway - Synced with main subversion repository at
greenmail ★ 744 Official master for the Greenmail project
faction ★ 604 Pen Test Report Generation and Assessment Collaboration
mesh ★ 593 Gentics Mesh - The open source headless CMS for developers
jivejdon ★ 588 Jivejdon is a chain notebook with DDD/CQRS/Clean architecture
Smithereen ★ 546 Federated, ActivityPub-compatible social network server with friends, walls, and groups.
Gravitee ★ 456 Unified API, event, and AI agent management platform
ClearFlask ★ 451 Open-source ideation tool for product feedback management
Convertigo ★ 385 Low-code and no-code platform for business apps
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Frequently asked questions
How many open source projects are written in Java?
This registry tracks 101 Java projects, with 1,171,051 GitHub stars between them and a median of 7,374 stars. The most-adopted is mall at 84,789 stars.
Which Java projects are most actively maintained?
92 of the 101 projects were pushed in the last 90 days. Each entry above shows its exact last-push date, so you can filter out dormant projects before committing to one.
What licence are Java projects usually under?
93 of the 101 carry an explicit open-source licence across 10 distinct licences, and the licence is shown on every card. Permissive licences (MIT, Apache-2.0) are the safest default for commercial use; check the copyleft ones individually.
Should I use Java or Kotlin for my project?
Both are viable. Java is the better default if your team already knows it or the libraries you need are written in it; Kotlin may suit you better if you need the ecosystem, tooling or performance profile it is known for. The registry lists 101 Java projects to work from.