Top 20+ Open-Source Java Projects Every Developer Should Try!
By Sriram
Updated on Jul 15, 2025 | 23 min read | 58.71K+ views
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By Sriram
Updated on Jul 15, 2025 | 23 min read | 58.71K+ views
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Did you know? AI is changing Java development. 60% of developers are using AI tools like ChatGPT and GitHub Copilot for code completion, 39% for refactoring, and 30% for error detection. These intelligent assistants are quickly becoming indispensable in the development workflow, helping developers save time and enhance productivity. |
Some prominent open-source Java projects include Apache Kafka, Elasticsearch, and Spring Boot. These projects are widely used in big data, cloud computing, and real-time analytics.
Working on such projects helps enhance your skills in distributed systems and data management. Java remains essential in developing scalable solutions within these open-source ecosystems.
In this blog, we'll explore top Java projects that offer hands-on experience and career growth opportunities.
In 2025, Integrated open-source Java projects will provide practical learning experiences, especially in machine learning. These projects enable developers to hone their skills in Java, cloud computing, and practical data systems.
To further enhance your Java expertise, consider exploring these industry-relevant courses, designed to refine your technical skills.
Here are some of the prominent open-source Java projects that you can select for building scalable applications.
Source: GitHub
Design Patterns in Java provide reusable solutions to common software design challenges, offering developers standardized approaches for creating scalable and maintainable software. By following these patterns, developers can streamline the design process, keep their code clean, and avoid common pitfalls.
Use Case:
Working on a large-scale e-commerce platform, Java design patterns such as the Singleton and Factory patterns can help create a modular and scalable system. The Singleton pattern manages database connections efficiently, while the Factory pattern enables dynamic creation of product types, making the code adaptable and maintainable.
Key Skills You Learn:
Tools You Need for This Project:
Also Read: Software Design Patterns: A Complete Guide for 2025
Source: Arduino
Arduino is an open-source electronics platform that blends simple hardware and software to create interactive projects. It provides a versatile foundation for controlling sensors, motors, lights, and other devices, supported by a strong community..
Use Case:
An automated garden system is a great example of using Arduino. By setting up sensors to monitor soil moisture levels and automate watering, Arduino enables smarter, more efficient solutions for projects.
Key Skills You Learn:
Tools You Need for This Project:
Also Read: Top 7 Arduino Projects Ideas & Topics For Beginners
Source: Blynk
Blynk is an open-source platform that simplifies mobile app development for IoT component projects, enabling developers to control and monitor hardware devices via smartphones or tablets. Its user-friendly drag-and-drop interface allows for easy creation of custom mobile interfaces, streamlining IoT system prototyping and deployment.
Use Case
Blynk can be used in smart home projects to control and monitor devices like lighting, security cameras, and HVAC systems via a mobile phone. It makes IoT technology accessible and customizable, enabling homeowners to personalize and automate their living spaces remotely.
Key Skills You Learn
Tools You Need for This Project
To get started with a Blynk-based IoT project, you will need the following tools and technologies:
Also Read: Top Java Courses for 2025 – Developer Approved Picks
Source: Strongbox
Strongbox is an open-source repository management system focused on security, encryption, and key management. It offers a secure platform for teams to manage sensitive data and cryptographic keys, making it an excellent project for developers interested in Java-based security and encryption.
Use Case
Strongbox securely stores and manages API keys, authentication tokens, and other sensitive configurations in enterprise software environments. By encrypting data and ensuring industry compliance, it prevents unauthorized access and data breaches, making it essential for secure key management.
Key Skills You'll Learn
Tools You Need for This Project
To build and contribute to Strongbox, you'll need familiarity with:
Also Read: 50 Java Projects With Source Code in 2025: From Beginner to Advanced
Source: Glasscutter
Glasscutter is an open-source framework designed for cross-platform UI testing in Java applications, automating the process across Windows, macOS, and Linux. It helps developers save time on manual testing while ensuring a consistent user experience and flawless functionality across platforms.
Use Case:
Glasscutter is a tool for Java developers that automates the testing of UI elements, such as buttons and text fields, ensuring they function as expected across various operating systems. It helps you verify your app's UI behaviour, whether you're building for a specific platform or a cross-platform app, without extensive manual checks.
Key Skills You Learn:
Tools You Need for This Project
Source: JabRef
JabRef is an open-source reference management tool that helps researchers and developers organize their bibliographic data effectively. It is especially popular in fields like computer science and engineering due to its LaTeX integration and support for multiple citation styles.
Use Case:
JabRef is a powerful tool for academic researchers to manage and format references for research papers, automating LaTeX-compatible citation lists with BibTeX and BibLaTeX support. Its advanced search and filtering features help manage large reference collections, allowing researchers to focus on their work instead of citation formatting.
Key Skills You'll Learn:
Tools You Need for This Project:
Also read: Top 27 SQL Projects in 2025 With Source Code: For All Levels
Source: Wikimedia Commons App
The Wikimedia Commons App is an open-source mobile application that allows users to browse, upload, and contribute to Wikimedia Commons, a vast collection of free-use media files. It combines mobile development, media management, and API integration, offering a great opportunity for developers interested in open-source Java projects.
Use Case
The Wikimedia Commons App is a valuable tool for educators, students, and creatives to easily upload, share, and access free-use media. It enables users to contribute to the global content repository and connect with a worldwide community directly from their mobile devices.
Key Skills You Learn
Tools You Need for This Project
Source: Robolectric
Robolectric is an open-source testing framework that enables developers to write unit tests for Android apps without using an emulator or physical device. It simulates Android’s framework on the JVM, boosting test speed and efficiency, making it essential for developers aiming to deliver high-quality apps quickly.
Use Case:
Robolectric enables developers to simulate Android components, such as Views and Activities, on a local machine, making it ideal for testing UI interactions. It speeds up development by providing a faster, in-memory testing environment and supports multiple Android versions, ensuring consistent tests across devices.
Key Skills You Learn:
Tools You Need for This Project
Source: Apache Tika
Apache Tika is an open-source framework that helps developers extract text, metadata, and language from various file formats. It automates content detection and extraction, making it a valuable tool for data management and document processing.
Use Case:
Apache Tika can be used to build a legal search engine by extracting text and metadata from various file formats like PDFs, Word documents, and images. Its powerful parsing capabilities enable efficient document indexing and fast, accurate searches through large repositories.
Key Skills You Learn:
Tools You Need for This Project:
Source: GitHub
Sndcpy is an open-source tool that lets you stream both audio and video from an Android device to a computer via USB or Wi-Fi, with minimal latency. It's widely used for app testing, presentations, and gaming, offering a fast and reliable way to mirror your device's display.
Use Case
Sndcpy is ideal for developers testing Android apps in real-time by mirroring the Android screen on a larger display. It’s also useful for presentations, enabling users to showcase mobile apps without a complex setup.
Key Skills You Learn
Tools You Need for This Project
USB and TCP/IP Protocols: Required to manage communication between your Android device and computer over different interfaces.
Also Read: How to Code, Compile, and Run Java Projects: A Beginner’s Guide
Source: Elasticsearch
Elasticsearch is a fast distributed search and analytics engine designed for real-time search across large datasets. It is commonly used in log analysis, full-text search, and business intelligence applications, making it essential for big data and distributed operating systems.
Use Case
Elasticsearch enables you to index logs from various sources, allowing for quick searches through massive datasets to detect real-time cybersecurity threats. Similarly, for business intelligence, it helps index transaction data, providing real-time search capabilities to analyze sales trends and customer behavior for quicker, data-driven decisions.
Key Skills You’ll Learn
Tools You Need for This Project
Source: Zerocode
Zerocode is an open-source framework that simplifies automated testing for Java-based applications, enabling developers and testers to write clear, human-readable test cases. With minimal configuration, it streamlines integration and end-to-end testing, making it ideal for teams working with microservices or RESTful APIs.
Use Case:
Zerocode is ideal for teams working with microservices architecture, automating API endpoint testing to ensure service interaction. It supports parallel test execution, speeding up feedback and making it perfect for automating regression tests and improving web service reliability in complex applications.
Key Skills You Learn:
Tools You Need for This Project:
To get started with Zerocode, you'll need:
Source: SirixDB
SirixDB is an open-source, versioned database designed to handle large-scale, transactional data while enabling the tracking and retrieval of data changes over time. It’s ideal for projects requiring real-time analysis and long-term storage, particularly for use cases that need to maintain a record of data evolution, such as time-series data.
Use Case:
SirixDB is ideal for Internet of Things (IoT) solutions, where sensor data needs long-term storage and monitoring. Its versioning capabilities allow you to track every data update, making it perfect for applications like environmental monitoring, smart cities, and predictive analytics.
Key Skills You Learn:
Tools You Need for This Project:
Also read: 33+ Data Analytics Project Ideas to Try in 2025 For Beginners and Professionals
Source: dotCMS
dotCMS is a powerful, open-source content management system (CMS) built using Java, designed for managing digital content across various platforms. With its focus on scalability and flexibility, dotCMS caters to businesses of all sizes, from small startups to large enterprises.
Use Case:
dotCMS is perfect for large-scale, multi-platform content management, ideal for enterprises delivering personalized experiences across websites, apps, and IoT. With versioning and approval workflows, it streamlines content creation, review, and distribution for high-volume teams.
Key Skills You Learn:
Tools You Need for This Project:
To get started with dotCMS, you’ll need the following tools and technologies:
Also Read: Careers in Java: How to Make a Successful Career in Java in 2025
Source: GitHub
GraalVM is an open-source, high-performance virtual machine that supports multiple languages like Java, JavaScript, Python, and Ruby. It enables multi-language execution within a single JVM, boosting performance and interoperability for modern applications.
Use Case
GraalVM is ideal for microservices where services are written in different languages like Java and Python. It allows them to run efficiently on the same JVM, simplifying development and reducing runtime overhead.
Key Skills You Learn
Tools You Need for This Project
To start working with GraalVM, you'll need the following tools:
Source: GitHub
OpenSearch is an open-source search and analytics engine, built on Elasticsearch, designed for fast, scalable, real-time search solutions. Ideal for data-heavy platforms like e-commerce and monitoring, it offers powerful full-text search and advanced analytics.
Use Case
OpenSearch powers fast, accurate product searches on e-commerce platforms by indexing product data efficiently. It also enables real-time analytics to track sales trends and user behavior, helping businesses make smarter decisions.
Key Skills You'll Learn
Tools You Need for This Project
To get started with OpenSearch, you'll need:
Also Read: Top 20 Spring Boot Features for Java Developers
Source: Thingsboard
ThingsBoard is an open-source IoT platform that helps collect, process, and visualize data from various devices. Its flexible architecture supports industries like manufacturing, agriculture, and smart cities, enabling scalable and efficient IoT solutions.
Use Case:
ThingsBoard enables real-time data collection from IoT devices like traffic lights, pollution sensors, and weather stations in smart cities. Its customizable dashboards help officials monitor conditions and make data-driven decisions for better urban planning and resource management.
Key Skills You Will Learn:
Tools You Need for This Project:
Apache Cassandra & PostgreSQL : Databases for managing the large amounts of data generated by IoT devices.
Source: Mindustry
Mindustry is an open-source strategy game blending resource management, RTS, and tower defense. It challenges players to build supply chains, automate production, and defend against waves of enemies. A great project for Java developers to explore complex systems and multiplayer game mechanics.
Use Case:
Mindustry is a great open-source project for aspiring game developers, focusing on resource management, automation, and multiplayer gameplay. It offers hands-on experience in optimizing performance and building complex, engaging mechanics.
Key Skills You Learn:
Tools You Need for This Project:
Also Read: Top 19 Spring Boot Projects With Source Course in 2025 for Beginners
Source: Hyperledger Fabric
Hyperledger Fabric is an open-source, permissioned blockchain framework built for enterprises. Its modular design allows businesses to create secure and efficient networks, supporting complex transactions with strong privacy and compliance features.
Use Case:
Hyperledger Fabric is widely used in supply chain solutions to ensure transparency and security by tracking goods from manufacturers to consumers. It creates an immutable, auditable record of transactions, improving efficiency and reducing fraud.
Key Skills You Learn:
Tools You Need for This Project:
To work with Hyperledger Fabric, you will need to be familiar with the following tools and technologies:
Also read: 14 Best Docker Project Ideas For Beginners
Source: JHipster
JHipster is an open-source platform that streamlines the development of modern web apps and microservices using Java, Spring Boot, and frontend frameworks like Angular, React, or Vue. It lets developers generate full-stack code quickly, making it perfect for building scalable, robust applications with ease.
Use Case:
JHipster simplifies web app development for e-commerce by offering a microservices architecture that supports rapid, scalable deployment. It integrates with APIs and cloud platforms like AWS and Azure, making it ideal for both small projects and enterprise-scale solutions.
Key Skills You Learn:
Tools You Need for This Project:
Also read: 35 Must-Know Spring Boot Annotations to Accelerate Your Development!
Source: Spring Boot
Spring Boot is an open-source Java framework that simplifies building stand-alone, production-ready applications. It reduces boilerplate code with pre-configured templates, making development faster and more efficient.
Use Case:
Spring Boot makes it easy to build and deploy a RESTful API for a logistics company, handling database integration, user authentication, and third-party shipping systems. It streamlines setup so you can focus on functionality and scalability.
Key Skills You'll Learn
Tools You Need for This Project
Also Read: 40 Must-Try JavaScript Project Ideas for Developers of All Levels
To make meaningful contributions, it’s crucial to evaluate key factors when selecting the right open-source Java project.
Selecting the right open source Java project depends on several factors. Here's what to consider when choosing a project:
Also read: 15 Essential Java Full Stack Developer Skills in 2025
Let’s explore some of the common mistakes you can avoid when working with open-source Java projects, when working with SQL, Spark, and more.
Contributing to open-source Java projects offers valuable learning experiences, but common mistakes can hinder your growth. Avoiding these errors will lead to better collaboration and more substantial contributions to open-source Java projects.
Here’s a tabular representation of the challenges and solutions:
Challenge | Solution |
Not reading project documentation | Always read the README and contribution guide for any open-source Java project, especially when working with SQL or Spark. |
Ignoring code style guidelines | Adhere to the project's coding conventions, whether using Java, Flask, or integrating with Spark frameworks. |
Writing vague commit messages | Write clear, detailed commit messages to explain your changes, especially for complex integrations like SQL queries or Flask APIs. |
Not testing code before submitting | Thoroughly test your code, including SQL queries, Flask APIs, or Spark transformations, before contributing. |
Failing to communicate with maintainers | Engage with project maintainers, especially when dealing with complex tools like Spark or Flask, for valuable feedback. |
Also Read: What Is Project Planning? A Complete Guide to the Project Lifecycle and Planning Process (2025)
Some popular open-source Java projects include JabRef, Zerocode, and GraalVM. Exploring these open-source Java projects will deepen your development skills and broaden your understanding of modern tools.
However, developers often struggle with managing complex codebases and integration challenges. upGrad can guide you through these challenges with structured learning and hands-on projects.
For further success, explore additional upGrad resources that offer in-depth courses and expert mentorship.
You can contact upGrad's expert career counselors, who will guide you based on your technical demands and learning curve with programming languages such as Java. You can also visit a nearby upGrad offline centre to explore course options, gain hands-on experience, and speak directly with mentors.
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References:
https://www.jrebel.com/blog/developer-report-highlights
https://spring.io/projects/spring-boot
https://www.jhipster.tech/
https://hyperledger-fabric.readthedocs.io/en/release-2.5/
https://mindustrygame.github.io/
https://thingsboard.io/
https://www.dotcms.com/
https://sirix.io/
https://www.jabref.org/
https://www.zeroco.de/
https://www.elastic.co/elasticsearch
https://tika.apache.org/
https://robolectric.org/
https://commons.wikimedia.org/wiki/Main_Page
https://www.curseforge.com/minecraft/mc-mods/glasscutter
https://strongboxsafe.com/
https://blynk.io/
https://www.arduino.cc/
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