Browse free open source Java Libraries and projects below. Use the toggles on the left to filter open source Java Libraries by OS, license, language, programming language, and project status.

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  • 1
    Java Neural Network Framework Neuroph
    Neuroph is lightweight Java Neural Network Framework which can be used to develop common neural network architectures. Small number of basic classes which correspond to basic NN concepts, and GUI editor makes it easy to learn and use.
    Downloads: 51 This Week
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  • 2
    JTS Topology Suite

    JTS Topology Suite

    Java library for creating and manipulating vector geometry.

    The JTS Topology Suite is a Java library for creating and manipulating vector geometry. It also provides a comprehensive set of geometry test cases, and the TestBuilder GUI application for working with and visualizing geometry and JTS functions.
    Downloads: 10 This Week
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  • 3
    A Java JNA wrapper for Tesseract OCR API
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    Downloads: 57 This Week
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  • 4
    AtlantaFX

    AtlantaFX

    Modern JavaFX CSS theme collection with additional controls

    Modern JavaFX CSS theme collection with additional controls.
    Downloads: 8 This Week
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  • 5
    Glide

    Glide

    Android image loading & caching library focused on smooth scrolling

    Glide is a fast and efficient open source image loading and caching library for Android that focuses on smooth scrolling. It supports fetching, decoding and displaying images, video stills as well as animated GIFs, with a simple and easy to use interface and API. Glide offers a performant and extensible resource decoding pipeline and automatic resource pooling, and a flexible API that allows developers to plug in to just about any network stack. It is primarily focused on making any type of a list of images as smooth and fast as possible, and is able to achieve this through smart and automatic downsampling and caching, aggressive re-use of resources and deep lifecycle integration. Apart from smooth and speedy scrolling, it’s also good for any case where fetching, resizing, and displaying of a remote image is needed.
    Downloads: 7 This Week
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  • 6
    JDA Java Discord API

    JDA Java Discord API

    Java wrapper for the popular chat & VOIP service

    JDA strives to provide a clean and full wrapping of the Discord REST api and its Websocket-Events for Java. This library is a helpful tool that provides the functionality to create a discord bot in java. Discord is currently prohibiting creation and usage of automated client accounts (AccountType.CLIENT). We have officially dropped support for client login as of version 4.2.0! Note that JDA is not a good tool to build a custom discord client as it loads all servers/guilds on startup unlike a client which does this via lazy loading instead. If you need a bot, use a bot account from the Application Dashboard.
    Downloads: 7 This Week
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  • 7
    PSI Probe

    PSI Probe

    Advanced manager and monitor for Apache Tomcat

    Advanced manager and monitor for Apache Tomcat, forked from Lambda Probe. Generally supported versions for third-party tomcat providers align with their support but earlier versions may still work. It is advisable in every case to use only supported tomcat releases per specific vendor. Our support will only be against non-CVE releases.
    Downloads: 7 This Week
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  • 8
    jclasslib bytecode editor

    jclasslib bytecode editor

    Visualizes all aspects of compiled Java class files

    jclasslib bytecode editor is a tool that visualizes all aspects of compiled Java class files and the contained bytecode. Many aspects of class files can be edited in the UI. In addition, it contains a library that enables developers to read and write Java class files and bytecode. All constant pool entries can be edited. Referenced constant pool entries can directly be edited from the context menu that is shown by the "Edit" button of attributes and constant pool entries. Bytecode instructions can be edited from the context menu.
    Downloads: 7 This Week
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  • 9
    iText®, a JAVA PDF library

    iText®, a JAVA PDF library

    PDF Library for Developers

    iText is an open-source PDF library available for Java and .NET (C#). iText allows you to effortlessly generate and manipulate standards-compliant PDF documents with a powerful and feature-rich SDK. With iText, you can create archivable and accessible PDFs, split and merge documents, fill and flatten forms, digitally sign documents, and more. iText add-ons enable additional functionality, such as PDF creation from HTML templates, secure redaction, OCR, and much more. The latest versions of iText build on the success of previous versions and feature an improved document engine, high and low-level programming capabilities, and a more efficient modular structure. iText represents the next level for developers looking to leverage PDF in document workflows. The main project page for iText is now on GitHub, and all the latest releases, code samples, open source add-ons and tools, etc. can be found at https://github.com/itext/.
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    Downloads: 174 This Week
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  • 10
    ImGui Java

    ImGui Java

    JNI based binding for Dear ImGui

    imgui-java is a comprehensive Java binding for Dear ImGui, the popular immediate-mode GUI library used for real-time tools and debug interfaces. This binding allows Java applications—including those using LWJGL or JOGL—to leverage ImGui’s fast and flexible GUI features without switching languages. With support for native backends and OpenGL rendering, imgui-java is perfect for game engines, development tools, and editors that need an intuitive GUI system. It includes integrations for multiple platforms and rendering contexts, with regular updates to match upstream ImGui releases.
    Downloads: 6 This Week
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  • 11
    JFlex

    JFlex

    The fast scanner generator for Java™ with full Unicode support

    JFlex is a lexical analyzer generator for Java, designed to create fast and efficient scanners. It takes regular expression specifications and produces Java code for tokenizing input text. ​
    Downloads: 6 This Week
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  • 12

    ConcatPDF

    PDF Concatenation Tool

    ConcatPDF is the tool to concatenate PDF files. It can concatenate, extract, encrypt, decrypt, configure PDF files, convert image files to PDF. GUI version and CUI version are both available. iText.NET is iText porting on .NET Framework by J#. This library allows you to generate PDF, (X)HTML, XML, RTF files on Microsoft.NET Framework including ASP.NET.
    Downloads: 38 This Week
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  • 13
    7-Zip-JBinding

    7-Zip-JBinding

    Java wrapper for 7z archiver engine

    Native (JNI) cross-platform library to extract (password protected, multi-part) 7z Zip Rar Tar Split Lzma Iso HFS GZip Cpio BZip2 Z Arj Chm Lhz Cab Nsis Deb Rpm Wim Udf archives and create 7z, Zip, Tar, GZip & BZip2 from Java.
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    Downloads: 37 This Week
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  • 14
    Android Interview Questions

    Android Interview Questions

    Your Cheat Sheet For Android Interview

    This repository is a comprehensive study guide for Android interviews, organized to cover the platform from fundamentals to advanced topics. It includes explanations and Q&A on the Android app lifecycle, activities and fragments, services, broadcast receivers, content providers, and the build system. Modern practices are addressed as well—Kotlin language features, coroutines, Jetpack components, MVVM/MVI architecture, dependency injection, and testing strategies. Performance and reliability topics receive attention, such as memory management, threading, WorkManager, networking, and offline storage patterns. The content favors concise, practical answers that interviewers expect, helping candidates rehearse concepts and trade-offs rather than memorize trivia. It’s equally useful for brushing up before an interview and for leveling up day-to-day Android engineering knowledge.
    Downloads: 5 This Week
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  • 15
    Asciidoc Editor based on JavaFX 20

    Asciidoc Editor based on JavaFX 20

    Asciidoc Editor and Toolchain written with JavaFX 19

    Asciidoc FX is a WYSIWYG editor for the Asciidoc markup language. You can build PDF, Epub, and HTML books, documents, and slides. Supported Operating Systems and Builds shows the list of available builds with links for reference. If you are looking for the very latest version, visit the link in the note above to be guaranteed of downloading the latest and greatest version of AsciidocFX. AsciidocFX converts documents via the AsciidoctorJ library.
    Downloads: 5 This Week
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  • 16
    Google Maps SDK for Android Samples

    Google Maps SDK for Android Samples

    Samples demonstrating how to use Maps SDK for Android

    Create dynamic, interactive and personalized experiences with maps, locations and geospatial experiences for your Android apps. Create an account, generate an API key, and start creating. Learn how to load the Maps SDK for Android and add a map with a bookmark to your web application. You can customize almost all aspects of the map, such as routes, landforms and places of interest, among others. Find the current location of an Android device and display details of the place or other place of interest in that location. Add bookmarks to a map, interact with click events, customize color and image, and more. Displays an information window with additional data and context when users press a bookmark. Customize user interaction by configuring integrated UI components and gestures. Listen to events on the map, including clicks on maps, clicks on markers, camera changes, and overlay events, among others.
    Downloads: 5 This Week
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  • 17
    Heritrix

    Heritrix

    Internet Archive's open-source, web-scale, web crawler project

    Heritrix is the Internet Archive's open-source, extensible, web-scale, archival-quality web crawler project. Heritrix (sometimes spelled heretrix, or misspelled or missaid as heratrix/heritix/heretix/heratix) is an archaic word for heiress (woman who inherits). Since our crawler seeks to collect and preserve the digital artifacts of our culture for the benefit of future researchers and generations, this name seemed apt. Heritrix is designed to respect the robots.txt exclusion directives† and META nofollow tags. Please consider the load your crawl will place on seed sites and set politeness policies accordingly. Also, always identify your crawl with contact information in the User-Agent so sites that may be adversely affected by your crawl can contact you or adapt their server behavior accordingly.
    Downloads: 5 This Week
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  • 18
    MCProtocolLib

    MCProtocolLib

    A library for communication with a Minecraft client/server

    MCProtocolLib is a simple library for communicating with Minecraft clients and servers. It allows developers to build custom bots, clients, or servers for Minecraft with ease.
    Downloads: 5 This Week
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  • 19
    Spoon

    Spoon

    Metaprogramming library to analyze and transform Java source code

    Spoon is an open-source library to analyze, rewrite, transform, transpile Java source code. It parses source files to build a well-designed AST with powerful analysis and transformation API. It supports modern Java versions up to Java 20. Spoon is an official Inria open-source project, and member of the OW2 open-source consortium.
    Downloads: 5 This Week
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  • 20
    Zeebe

    Zeebe

    Distributed Workflow Engine for Microservices Orchestration

    Automate processes at scale with unprecedented performance and resilience. Zeebe is the workflow and decision engine that powers Camunda Platform 8. Zeebe’s cloud-native design provides the performance, resilience, and security enterprises need to future-proof their process orchestration efforts. Zeebe distributes data across all brokers in a cluster with storage directly on the server filesystem. If one broker goes down, another can replace it with no data loss. This pre-configured replication mechanism ensures that Camunda Platform 8 can recover from machine or software failure with no human interaction, no data loss and minimal downtime.
    Downloads: 5 This Week
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  • 21
    tlaplus

    tlaplus

    TLC is an explicit state model checker for specifications in TLA+

    TLC is an explicit state model checker for specifications written in TLA+. The TLA+Toolbox is an IDE for TLA+. TLA+ is a high-level language for modeling programs and systems--especially concurrent and distributed ones. It's based on the idea that the best way to describe things precisely is with simple mathematics. TLA+ and its tools are useful for eliminating fundamental design errors, which are hard to find and expensive to correct in code.
    Downloads: 5 This Week
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  • 22
    JDatePicker: Java Swing Date Picker

    JDatePicker: Java Swing Date Picker

    This project now lives at: https://github.com/JDatePicker/JDatePicker

    This project now lives at: https://github.com/JDatePicker/JDatePicker Will keep this sf.net project active to point to github. JDatePicker and JDatePanel is an set of advanced DatePicker controls for Java Swing applications. The MVC design enables us to display any date object such as Joda-Time DateMidnight. The date picker also works well with JGoodies Binding.
    Downloads: 25 This Week
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  • 23
    Booklore

    Booklore

    Digital library with smart shelves

    Booklore is a comprehensive self-hosted digital library platform that helps readers organize, manage, track, and even read their personal collections of books and comics from a centralized web interface. It provides powerful metadata management that automatically fetches rich details like titles, authors, covers, and publication info so your library looks organized and beautiful without manual data entry. Users can create smart shelves with custom filters, build dynamic collections that update automatically, and search through thousands of entries instantly, turning chaotic folders of files into a curated reading experience. Booklore supports multi-user access with granular permission controls, making it suitable for families, book clubs, or shared collections, and its built-in reader can display PDFs, EPUBs, and comic formats directly in a browser.
    Downloads: 4 This Week
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  • 24
    MongoDB JVM Driver

    MongoDB JVM Driver

    The MongoDB drivers for Java, Kotlin, and Scala

    Welcome to the documentation site for the Java Driver, the MongoDB driver for synchronous Java applications. Download it using Maven or Gradle, or set up a runnable project by following our Quick Start guide. For tutorials on how to use the MongoDB JVM Drivers, please reference MongoDB University. Additional tutorials, videos, and code examples using both the Java Driver and the Kotlin Driver can also be found in the MongoDB Developer Center.
    Downloads: 4 This Week
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  • 25
    jsoup

    jsoup

    Java library for working with real-world HTML

    jsoup is a Java library for working with real-world HTML. It provides a very convenient API for fetching URLs and extracting and manipulating data, using the best of HTML5 DOM methods and CSS selectors. jsoup implements the WHATWG HTML5 specification, and parses HTML to the same DOM as modern browsers do. jsoup is designed to deal with all varieties of HTML found in the wild; from pristine and validating, to invalid tag-soup; jsoup will create a sensible parse tree. The parser will make every attempt to create a clean parse from the HTML you provide, regardless of whether the HTML is well-formed or not. You have HTML in a Java String, and you want to parse that HTML to get at its contents, or to make sure it's well formed, or to modify it. The String may have come from user input, a file, or from the web.
    Downloads: 4 This Week
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