Java HacktoberFest

Open-source Java projects categorized as HacktoberFest

Top 23 Java HacktoberFest Projects

  • Design Patterns

    Design patterns implemented in Java

    Project mention: I have been following the mooc java-1 from few days and i am on part-3 i want to ask some questions | /r/learnjava | 2023-06-06

    After that, more practice, and then Design Patterns (as in the famous book of the "Gang of Four": "Design Patterns: Elements of Reusable Object Oriented Software"). Here I'd recommend "Head First: Design Patterns" and Java Design Patterns as well as Refactoring Guru (the sites are more reference than course).

  • Java

    All Algorithms implemented in Java

  • WorkOS

    The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

  • termux-app

    Termux - a terminal emulator application for Android OS extendible by variety of packages.

    Project mention: Utilize AI-powered Tools Amazon CodeWhisperer and Amazon Q in Visual Studio Code on Android Devices | | 2024-01-23

    Download Termux latest version.

  • Jenkins

    Jenkins automation server

    Project mention: 20 Things You Should Consider When You Grow as a Developer | | 2024-02-19

    Familiarize yourself with tools like Jenkins, Travis CI, GitLab CI, and others that facilitate these practices.

  • JHipster

    JHipster, much like Spring initializr, is a generator to create a boilerplate backend application, but also with an integrated front end implementation in React, Vue or Angular. In their own words, it "Is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures."

    Project mention: Java Microservices with Spring Boot and Spring Cloud | | 2024-01-11

    An easy way to get a pre-configured Keycloak instance is to use JHipster's jhipster-sample-app-oauth2 application. It gets updated with every JHipster release. You can clone it with the following command:

  • Apache RocketMQ

    Apache RocketMQ is a cloud native messaging and streaming platform, making it simple to build event-driven applications.

    Project mention: Critical Analysis: Unraveling the Apache RocketMQ Remote Code Execution Vulnerability (CVE-2023-33246) | | 2023-07-29
  • shardingsphere

    Distributed SQL transaction & query engine for data sharding, scaling, encryption, and more - on any database.

    Project mention: Managing Data Residency - the demo | | 2023-05-25

    Opposite to what the documentation tells, the full prefix is jdbc:shardingsphere:absolutepath. I've opened a PR to fix the documentation.

  • InfluxDB

    Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

  • openapi-generator

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

    Project mention: OpenAPI Generator v7.3.0 has new generators for Rust, Kotlin, Scala and Java | | 2024-02-08
  • QuestDB

    An open source time-series database for fast ingest and SQL queries

    Project mention: Normalizing Grafana charts with window functions | | 2024-01-10

    If you're interested in that functionality or have any other feedback, please drop by our open source repository or community Slack and let us know.

  • Quarkus

    Quarkus: Supersonic Subatomic Java.

    Project mention: How Netflix Uses Java | | 2024-02-27

    Meanwhile, if you're building something smaller than Netflix, I'm writing a book just for that (

    It's about mobile apps, but I talk about backend at great length, especially since my background is Java. The book is called "opinionated" because I cover Quarkus (, monolith,, and no K8s.

  • Apache ZooKeeper

    Apache ZooKeeper

    Project mention: Easy Guide to Integrating Kafka: Practical Solutions for Managing Blob Data | | 2024-01-22

    To use Kafka, we also need to deploy a service that keeps configuration informations such as Zookeeper.

  • ZAP

    The ZAP core project

    Project mention: Best Hacking Tools for Beginners 2024 | | 2024-02-01


  • SuperTokens Community

    Open source alternative to Auth0 / Firebase Auth / AWS Cognito

    Project mention: Auth0 increases price by 300% | /r/webdev | 2023-12-07

    Checkout - open source alternative to Auth0. It has a lot of free features and if you self host it, it's free at any scale. For our managed service, it's still far cheaper compared to Auth0.

  • android-gif-drawable

    Views and Drawable for displaying animated GIFs on Android

  • Paper

    The most widely used, high performance Minecraft server that aims to fix gameplay and mechanics inconsistencies

    Project mention: How to Setup a Minecraft Server on Ubuntu: A Step-by-Step Guide | | 2024-01-07

    We will be downloading the Minecraft server files into this directory. To preface, there are numerous variations of server JARs that can be used (e.g. Spigot, Paper, Purpur each touting their own benefits). For this tutorial, we will be working with Paper, a fork of Spigot that is optimized for performance.

  • OpenSearch

    🔎 Open source distributed and RESTful search engine.

    Project mention: Guiding Principles | | 2023-10-07
  • kafka-ui

    Open-Source Web UI for Apache Kafka Management

    Project mention: FLaNK Stack Weekly 16 October 2023 | | 2023-10-17
  • Testcontainers

    Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

    Project mention: Testcontainers | | 2024-02-27

    except the parent is wrong (at least the Java impl). see:

  • Aegis

    A free, secure and open source app for Android to manage your 2-step verification tokens.

    Project mention: End of Life for Twilio Authy Desktop App | | 2024-02-13

    For 1Password I use a Yubikey, but for 2FA in general, I have a backup phone running Aegis[1].


  • graylog

    Free and open log management

    Project mention: graylog VS openobserve - a user suggested alternative | | 2023-09-07
  • WireMock

    A tool for mocking HTTP services

    Project mention: Fastify Meets WireMock: External Service Mocking | | 2024-02-13

    This article reveals how to integrate WireMock into Fastify with ease, enabling developers to effortlessly generate mock responses for external services. Join us as we explore the straightforward process of seamlessly integrating and optimizing Fastify applications using WireMock for enhanced testing capabilities.

  • Hazelcast

    Hazelcast is a unified real-time data platform combining stream processing with a fast data store, allowing customers to act instantly on data-in-motion for real-time insights.

    Project mention: Does anyone know any good java implementations for distributed key-value store? | /r/ExperiencedDevs | 2023-06-08

    You're probably looking for Hazelcast here. Note that it does much more than just a distributed k/v, but it will get you where you need to go.

  • incubator-kie-drools

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

    Project mention: Open source rules engine for Magic: The Gathering | | 2023-12-14

    That's interesting, thank you. It seems what's old is new again: I had a lot of contact with CLIPS early in my career but I found that most of the programming tasks weren't heavy rules based as much as CRUD and reporting apps. Given that Forge is in Java, they may enjoy Drools <> (which used to be a JBoss project but I guess has been donated to the Apache Foundation)

  • 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). The latest post mention was on 2024-02-27.

Java HacktoberFest related posts


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

Project Stars
1 Design Patterns 85,865
2 Java 55,970
3 termux-app 29,098
4 Jenkins 22,123
5 JHipster 21,148
6 Apache RocketMQ 20,315
7 shardingsphere 19,264
8 openapi-generator 19,200
9 QuestDB 13,265
10 Quarkus 12,886
11 Apache ZooKeeper 11,826
12 ZAP 11,771
13 SuperTokens Community 11,306
14 android-gif-drawable 9,481
15 Paper 8,367
16 OpenSearch 8,340
17 kafka-ui 8,013
18 Testcontainers 7,656
19 Aegis 7,195
20 graylog 6,981
21 WireMock 6,002
22 Hazelcast 5,772
23 incubator-kie-drools 5,622
SaaSHub - Software Alternatives and Reviews
SaaSHub helps you find the best software and product alternatives