Top 20+ Open-Source Java Projects Every Developer Should Try!

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.

Top 20+ Open-Source Java Projects in 2025 in a Glance

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.

• Master of Design in User Experience
• Professional Certificate in Cloud Computing & DevOps
• AI and Full Stack Development Program

Here are some of the prominent open-source Java projects that you can select for building scalable applications. 

1. Java Design Patterns

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:

• Understanding core Object-Oriented Programming (OOP) principles like encapsulation, inheritance, and polymorphism.
• Designing software architectures that are scalable, maintainable, and efficient using proven design patterns.
• Gaining practical knowledge in applying design patterns to real-world problems enables you to develop robust and easily extensible systems.

Tools You Need for This Project:

• Java Programming Language: A strong foundation in Java is required, as it forms the basis for implementing design patterns.
• Object-Oriented Programming (OOP) Principles: Knowledge of OOP is essential to understanding how design patterns work within Java.
• Unified Modeling Language (UML): UML diagrams are often used to visualize design patterns and their relationships, helping you conceptualize your software architecture.
• IDE (Integrated Development Environment): A Java IDE like IntelliJ IDEA or Eclipse will facilitate the development and testing of your code.

Also Read: Software Design Patterns: A Complete Guide for 2025

2. Arduino

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:

• Working with embedded systems and hardware programming
• Writing code to interface with various sensors and actuators
• Understanding and implementing communication protocols like I2C, SPI, and UART
• Debugging hardware issues and optimizing system performance

Tools You Need for This Project:

• Arduino IDE: Integrated Development Environment for coding
• Arduino Board: Options like Uno, Nano, or Mega
• Programming Languages: C/C++ for coding the hardware interactions
• Sensors and Actuators: Such as temperature sensors, motors, and LEDs
• Communication Protocols: Familiarity with I2C, SPI, and UART
• Power Supply: To power your Arduino and connected components

Also Read: Top 7 Arduino Projects Ideas & Topics For Beginners

3. Blynk

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

• Mobile app development for controlling and monitoring IoT devices.
• Integration with cloud platforms and APIs for seamless device communication and data management.
• Understanding of real-time data transmission and secure communication protocols.
• Prototyping and deploying IoT solutions with minimal coding effort.

Tools You Need for This Project
To get started with a Blynk-based IoT project, you will need the following tools and technologies:

• Hardware: Arduino, ESP32, Raspberry Pi, or other IoT platforms.
• Software: Blynk mobile app (available for both iOS and Android), Blynk Cloud (for device communication and data storage).
• Communication Protocols: MQTT, HTTP, WebSockets, which enable real-time communication and data exchange between devices and the cloud.

Also Read: Top Java Courses for 2025 – Developer Approved Picks

4. Strongbox

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

• Implementing encryption and security protocols in Java.
• Working with RESTful APIs for secure data exchange.
• Managing cryptographic keys and ensuring compliance with security standards.

Tools You Need for This Project

To build and contribute to Strongbox, you'll need familiarity with:

• Java: For developing the core functionality of the project.
• Apache Maven: For managing the project's dependencies and build process.
• Spring Security: To implement security measures and encryption.
• JAX-RS (Java API for RESTful Web Services): For building and managing secure RESTful APIs.

Also Read: 50 Java Projects With Source Code in 2025: From Beginner to Advanced

5. Glasscutter

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:

• Writing automated UI tests for Java applications
• Debugging and resolving UI-related issues early in development
• Managing complex user interactions in test scripts
• Ensuring cross-platform compatibility for Java applications

Tools You Need for This Project

• Java: The programming language used to develop the application and Glasscutter framework
• JUnit: For testing Java applications and writing test cases
• Selenium: A tool for automating web browsers, which can also be used for UI testing in Java applications
• TestNG: A testing framework that works seamlessly with JUnit for effective test management

6. JabRef

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:

• Working with citation management and academic tools.
• Integrating third-party APIs for external data sources.
• Understanding the complexities of citation styles and formats.
• Synchronizing data across multiple devices.

Tools You Need for This Project:

• Java (Core Java skills required)
• JavaFX (for building the user interface)
• BibTeX, BibLaTeX (for citation management)
• LaTeX (for integration with LaTeX-based referencing systems)
• SQLite (for managing bibliographic data)

Also read: Top 27 SQL Projects in 2025 With Source Code: For All Levels

7. Wikimedia Commons App

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

• Mobile app development with Java and Kotlin for Android.
• Working with RESTful APIs for smooth data exchange.
• Implementing local data storage using SQLite.
• Building intuitive user interfaces that can handle large media files.
• Managing authentication and user access control for uploads and downloads.

Tools You Need for This Project

• Java and Kotlin: For Android development, allowing you to build the app's core functionalities.
• Wikimedia APIs: To connect and interact with the Wikimedia Commons repository.
• Retrofit: For efficient network communication and making API calls.
• SQLite: For local data storage, ensuring a seamless offline experience.

8. Robolectric

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:

• Writing fast, reliable unit tests for Android apps.
• Gaining a deeper understanding of the Android framework internals.
• Simulating real device behavior for more effective testing.

Tools You Need for This Project

• Java: The primary programming language for creating unit tests.
• Robolectric: The open-source testing framework itself.
• JUnit: The testing library for structuring and running tests.
• Android SDK: Essential for Android app development and integration.

9. Apache Tika

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:

• Document Parsing in Java: Learn how to parse and process text from different document types like PDFs, Microsoft Office files, and images.
• Content Extraction and Indexing: Gain hands-on experience with content extraction, a crucial skill for creating document search engines or data analysis tools.
• Working with OCR: Implement Optical Character Recognition (OCR) to extract text from image-based content.
• MIME Type Detection: Master the ability to detect and determine content types, which is crucial for processing various file formats.

Tools You Need for This Project:

• Java: Apache Tika is built on Java, so a strong foundation in Java is necessary to use it effectively.
• Apache Tika Core Library: The primary library for content extraction, which provides essential functionality for document parsing.
• Apache POI: A library to handle Microsoft Office formats like DOC, XLS, and PPT.
• PDFBox: A tool for working with PDF documents, enabling text extraction and metadata retrieval.
• Tesseract: An OCR engine that allows for the extraction of text from image files, an essential component of working with scanned documents.

10. Sndcpy

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

• Android ADB (Android Debug Bridge) integration: Learn how to use Android's native ADB features for device communication and screen mirroring.
• Low-latency audio and video streaming: Gain insights into optimizing multimedia transmission to ensure smooth and real-time mirroring.
• Synchronization techniques: Understand how to synchronize audio and video across devices, ensuring a seamless user experience.
• Network protocols and communication: Learn the use of USB and TCP/IP protocols to establish a reliable communication channel between devices.

Tools You Need for This Project

• C/C++: Core development language for the Sndcpy application.
• Android Debug Bridge (ADB): Essential for connecting Android devices to your computer for mirroring.
• Multimedia Encoding Libraries (e.g., FFmpeg): Used for encoding the video and audio streams to ensure efficient transmission.

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

11. Elasticsearch

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

• Working with RESTful APIs for data communication.
• Data indexing techniques and optimizing search algorithms for speed.
• Managing and querying large datasets in a distributed system environment.

Tools You Need for This Project

• Java: The primary language used for interacting with Elasticsearch.
• Elasticsearch: The engine for real-time search and analytics.
• Apache Lucene: The core search library behind Elasticsearch.
• JSON: For data exchange in Elasticsearch’s RESTful APIs.
• RESTful APIs: For integrating Elasticsearch with other systems and applications.

12. Zerocode

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:

• Writing and executing automated integration tests for Java-based applications.
• Working with RESTful APIs and testing the functionality of web services.
• Implementing parallel test execution for quicker validation.
• Developing maintainable and scalable test cases without the need for complex programming.

Tools You Need for This Project:

To get started with Zerocode, you'll need:

• Java: The core programming language for the framework.
• JSON/YAML: For structuring test data in a clear, readable format.
• JUnit: For integrating and running tests within the Java ecosystem for JUnit test in Java.
• RESTful APIs: Familiarity with testing and interacting with web services through API endpoints.

13. SirixDB

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:

• Learn to manage databases with version control and perform queries across different time periods.
•  Implement tree-based indexing for faster performance in large-scale time-series datasets.
• Explore techniques to manage dynamic, large-scale datasets while ensuring integrity and efficient retrieval.

Tools You Need for This Project:

• Java: SirixDB is built using Java, so familiarity with this programming language is essential.
• SirixDB Engine: You’ll need to work with the SirixDB core engine to implement versioning and time-series data handling.
• Tree-based Indexing: Understanding and implementing indexing techniques to optimize large-scale data storage and querying.
• Transactional Data Models: Knowledge of transactional systems and how they handle concurrent data modifications, ensuring consistency and reliability.

Also read: 33+ Data Analytics Project Ideas to Try in 2025 For Beginners and Professionals

14. dotCMS

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:

• Build CMS platforms that scale efficiently to support heavy traffic and large content repositories.
• Develop scalable backend systems using Java and the Spring architecture framework for efficient content management.
• Integrate templating engines like Freemarker to render dynamic, personalized content.
• Integrating CMS platforms with other systems and APIs for smooth cross-platform functionality.

Tools You Need for This Project:

To get started with dotCMS, you’ll need the following tools and technologies:

• Java: The primary language for building and extending dotCMS.
• Spring Framework: For creating robust, scalable applications within the dotCMS environment.
• Elasticsearch: For optimizing search functionality within the CMS.
• Freemarker: A templating engine for rendering dynamic content.
• MySQL/PostgreSQL: For managing content storage in databases.

Also Read: Careers in Java: How to Make a Successful Career in Java in 2025

15. GraalVM

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

• Developing multi-language applications using GraalVM's polyglot capabilities.
• Enhancing application performance with GraalVM's JIT (Just-in-Time) compilation and native-image tool.
• Gaining expertise in performance optimizations and memory management within the JVM ecosystem.

Tools You Need for This Project

To start working with GraalVM, you'll need the following tools:

• GraalVM (VM and JDK): The core virtual machine and JDK distribution.
• Native-image tool: Used for compiling applications ahead of time into native executables.
• Java, JavaScript, Python: Languages supported by GraalVM for multi-language development.

16. OpenSearch

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

• Implementing and managing search and analytics platforms in real time.
• Designing and building complex search systems with high scalability.
• Handling distributed systems and ensuring data consistency across multiple nodes.

Tools You Need for This Project

To get started with OpenSearch, you'll need:

• Java: For backend development and integrating OpenSearch into your applications.
• OpenSearch (Core Engine): The primary search and analytics engine.
• Apache Lucene: The underlying library for indexing and searching.
• RESTful APIs: For interacting with OpenSearch from your application.
• Kibana: For data visualization and analyzing trends.

Also Read: Top 20 Spring Boot Features for Java Developers

17. ThingsBoard

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:

• Build IoT systems using Java and the Spring Framework.
• Gain expertise in handling real-time data streams, processing large volumes of data, and implementing analytics.
• Complexities of managing and monitoring a large number of connected devices in a scalable environment.
• Create dynamic dashboards and widgets for real-time data representation.

Tools You Need for This Project:

• Java: The core programming language for developing the backend of ThingsBoard applications.
• Spring Framework: Essential for creating the necessary components to support IoT communication and management.
• MQTT: A messaging protocol used for real-time communication between devices and the server.

Apache Cassandra & PostgreSQL : Databases for managing the large amounts of data generated by IoT devices.

18. Mindustry

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:

• Game development techniques using Java and LibGDX (game development framework).
• Designing and optimizing resource management and logistics systems.
• Developing automation strategies and balancing game mechanics.
• Improving performance for multiplayer sessions, including handling resource-heavy simulations.

Tools You Need for This Project:

• Java: The primary programming language used to develop Mindustry, focusing on both gameplay logic and optimization.
• LibGDX: A powerful game development framework that supports cross-platform game creation.
• OpenGL: Utilized for rendering and graphical performance optimization.
• JSON: Used to configure game data and settings, making it crucial for modding and customization.

Also Read: Top 19 Spring Boot Projects With Source Course in 2025 for Beginners

19. Hyperledger Fabric

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:

• Developing and deploying blockchain applications with smart contracts (chaincode).
• Building and managing permissioned blockchain networks.
• Ensuring data privacy and secure participant management within a blockchain network.
• Integrating blockchain systems with existing enterprise solutions for streamlined operations.

Tools You Need for This Project:

To work with Hyperledger Fabric, you will need to be familiar with the following tools and technologies:

• Go Programming Language: Used for developing smart contracts (chaincode).
• Hyperledger Fabric SDK: Provides the necessary libraries to interact with the blockchain network.
• Docker: For containerizing and deploying the application.
• Kubernetes: For orchestrating the containers at scale.
• CouchDB: For storing data in a blockchain network.

Also read: 14 Best Docker Project Ideas For Beginners

20. JHipster

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:

• Building microservices-based applications for modularity and scalability.
• Integrating cloud-native architectures using DevOps tools like Docker and Kubernetes.
• Developing with a full-stack approach, handling both frontend (Angular/React/Vue) and backend (Spring Boot) components.
• Configuring Continuous Integration/Continuous Deployment (CI/CD) pipelines for seamless updates.

Tools You Need for This Project:

• Java and Spring Boot for backend development.
• Angular, React, and Vue are frontend frameworks.
• Docker and Kubernetes for containerization and deployment.
• PostgreSQL and MySQL for managing your data effectively.
• Cloud platforms, such as AWS or Azure, are ideal for hosting and scaling your application.

Also read: 35 Must-Know Spring Boot Annotations to Accelerate Your Development!

21. Spring Boot

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

• Building RESTful APIs and web applications with minimal setup.
• Integrating security, data access, and messaging frameworks into Spring Boot applications.
• Understanding how to develop and manage microservices architectures.

Tools You Need for This Project

• Java: The core programming language for the project.
• Spring Framework: A comprehensive framework for building Java applications.
• Spring Boot Starter Projects: Pre-configured templates to kickstart development.
• Maven/Gradle: Build tools for managing dependencies and project setup.
• Spring Security: Securing Your Application.
• Spring Data: To simplify database interactions.
• Spring Cloud: For creating microservice-based architectures.

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.

How to Choose 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:

• Experience level: Pick a project that matches your skill level. Beginners can start with simpler open-source Java projects, such as a calculator app or a basic game. At the same time, more advanced developers can explore social media platforms or contribute to Spring Boot projects.
• Interests and goals: Choose projects that align with your interests and career goals. This will help you stay motivated and focused while contributing to open-source Java projects.
• Balance complexity and learning: Look for projects that challenge you without being too overwhelming. A balanced level of difficulty ensures you're continuously learning and growing as a developer while still making progress on the project.
• Community support: Consider projects with an active community. Open-source Java projects with strong communities often have access to resources, mentors, and regular updates, which can make the development process smoother and more collaborative.
• Project documentation: Verify the presence of clear and comprehensive documentation. Good documentation in open-source Java projects ensures that you can understand the project structure, get started quickly, and contribute effectively.

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. 

What are Some Common Mistakes to Avoid in Open-Source Java Projects?

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:

Also Read: What Is Project Planning? A Complete Guide to the Project Lifecycle and Planning Process (2025)

How upGrad Can Help You Build a Career in Java Development?

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.

• Generative AI Mastery Certificate for Software Development
• Data Structures & Algorithms
• Java Object-oriented Programming

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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Source Codes:

• OpenSearch Source Code
• GraalVM Source Code
• sndcpy Source Code