Java HacktoberFest

Open-source Java projects categorized as HacktoberFest

Top 23 Java HacktoberFest Projects

  • Design Patterns

    Design patterns implemented in Java

    Latest mention: Top 10 Developer Trends, Mon Oct 12 2020 | | 2020-10-12

    iluwatar / java-design-patterns

  • Jenkins

    Jenkins automation server

    Latest mention: How CI/CD tools are built? | | 2021-01-21

    Jenkins is open source.

  • Sentinel

    A powerful flow control component enabling reliability, resilience and monitoring for microservices. (面向云原生微服务的高可用流控防护组件)

  • Apache ZooKeeper

    Apache ZooKeeper

  • Mindustry

    A sandbox tower defense game

    Latest mention: Is it possible to get v5? | | 2021-01-27
  • Zed

    The OWASP ZAP core project

  • openapi-generator

    OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec (v2, v3)

    Latest mention: Development of TypeScript Code Generator for OpenAPI Specification using AST | | 2021-01-12
  • junit5

    ✅ The 5th major version of the programmer-friendly testing framework for Java and the JVM

    Latest mention: How to detect all test classes in JUnit5 finish? | | 2021-01-16

    I was chasing similar problem, while I didn't find docs, and yet to try it, here is what I found so far. The idea is to use context closable store to be notified when things are done. Here is GitHub issue with an example: And here is some relevant PRs that were merged into JUnit5

  • Hazelcast

    Open Source In-Memory Data Grid

  • EdXposed

    Elder driver Xposed Framework.

    Latest mention: Signal and Android's Incognito Keyboard | | 2021-01-22

    I rooted my phone with magisk(Github), and used Afwall+(github), which is open source. Xprivacylua(github) is also open source, and needs the xposed framework to work. I use edxposed(github), which is pretty much a modern reimplementation of the legacy xposed framework.

  • Drools

    Drools is a rule engine, DMN engine and complex event processing (CEP) engine for Java.

    Latest mention: Design patterns for splitting up arbitrary business logic? | | 2020-12-29
  • AntennaPod

    A podcast manager for Android

    Latest mention: Appassionati Di Podcast Vi Presentiamo Due | | 2021-01-15

    Se non ti risponde nessun altro puoi provare a chiedere sulla pagina del progetto :)

  • Cucumber

    Cucumber monorepo - building blocks for Cucumber in various languages

  • Apache Cordova

    Apache Cordova Android

  • runelite

    Open source Old School RuneScape client

    Latest mention: How do I keep Runelite accounts separated over two clients? | | 2021-01-22

    See here.

  • Armeria

    Your go-to microservice framework for any situation, from the creator of Netty et al. You can build any type of microservice leveraging your favorite technologies, including gRPC, Thrift, Kotlin, Retrofit, Reactive Streams, Spring Boot and Dropwizard.

  • Crate

    CrateDB is a distributed SQL database that makes it simple to store and analyze massive amounts of machine data in real-time.

  • Traccar

    Traccar GPS Tracking System

  • OpenJ9

    Eclipse OpenJ9: A Java Virtual Machine for OpenJDK that's optimized for small footprint, fast start-up, and high throughput. Builds on Eclipse OMR ( and combines with the Extensions for OpenJDK for OpenJ9 repo.

  • jMonkeyEngine

    A complete 3D game development suite written purely in Java.

  • liquibase

    Main Liquibase Source

    Latest mention: Liquibase 3.x 4.x liquibase-compat and liquibase-percona | | 2021-01-20

    The getInstance() call should be added back as a deprecated method to help with the update. I created to track the fix

  • Openfire

    An XMPP server licensed under the Open Source Apache License.

  • Cucumber

    Cucumber for the JVM

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). The latest post mention was on 2021-01-27.


What are some of the best open-source HacktoberFest projects in Java? This list will help you:

Project Stars
1 Design Patterns 63,307
2 Jenkins 16,811
3 Sentinel 15,207
4 Apache ZooKeeper 9,055
5 Mindustry 8,414
6 Zed 8,155
7 openapi-generator 7,454
8 junit5 4,390
9 Hazelcast 4,165
10 EdXposed 3,761
11 Drools 3,448
12 AntennaPod 3,339
13 Cucumber 3,123
14 Apache Cordova 3,116
15 runelite 3,106
16 Armeria 2,921
17 Crate 2,904
18 Traccar 2,690
19 OpenJ9 2,550
20 jMonkeyEngine 2,539
21 liquibase 2,434
22 Openfire 2,279
23 Cucumber 2,244