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.

  • MicroStation by Bentley Systems is the trusted computer-aided design (CAD) software built specifically for infrastructure design. Icon
    MicroStation by Bentley Systems is the trusted computer-aided design (CAD) software built specifically for infrastructure design.

    Microstation enables architects, engineers, and designers to create precise 2D and 3D drawings that bring complex projects to life.

    MicroStation is the only computer-aided design software for infrastructure design, helping architects and engineers like you bring their vision to life, present their designs to their clients, and deliver their projects to the community.
    Learn More
  • Award-Winning Medical Office Software Designed for Your Specialty Icon
    Award-Winning Medical Office Software Designed for Your Specialty

    Succeed and scale your practice with cloud-based, data-backed, AI-powered healthcare software.

    RXNT is an ambulatory healthcare technology pioneer that empowers medical practices and healthcare organizations to succeed and scale through innovative, data-backed, AI-powered software.
    Learn More
  • 1
    Fresco

    Fresco

    An Android library for managing images and the memory they use

    Fresco’s image pipeline will load images from the network, local storage, or local resources. To save data and CPU, it has three levels of cache; two in memory and another in internal storage. Fresco’s Drawee shows a placeholder for you until the image has loaded and then automatically shows the image when it arrives. When the image goes off-screen, it automatically releases its memory. A decompressed image - an Android Bitmap - takes up a lot of memory. This leads to more frequent runs of the Java garbage collector. This slows apps down. The problem is especially bad without the improvements to the garbage collector made in Android 5.0. On Android 4.x and lower, Fresco puts images in a special region of Android memory. It also makes sure that images are automatically released from memory when they’re no longer shown on screen. This lets your application run faster - and suffer fewer crashes.
    Downloads: 7 This Week
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  • 2
    Google Cloud Dataflow Template Pipelines

    Google Cloud Dataflow Template Pipelines

    Cloud Dataflow Google-provided templates for solving data tasks

    DataflowTemplates is the source repository for Google-provided Dataflow templates that are intended to solve large-scale in-cloud data processing tasks without requiring users to build everything from scratch in a full development environment. The repository is centered on templated pipelines powered by Google Cloud Dataflow and Apache Beam, making it easier to run common integration and movement jobs such as data import, export, backup, restore, and bulk API operations. Its structure shows support for multiple generations of templates, including v1 and v2 implementations, as well as related metadata, YAML assets, plugins, and Python components that support broader template execution and maintenance. This design makes the project more than a sample set, because it acts as the implementation base for official Google-provided templates used in real cloud data workflows.
    Downloads: 7 This Week
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  • 3
    Hutool

    Hutool

    A set of tools that keep Java sweet

    Hutool is a small but comprehensive Java tool class library. Through static method encapsulation, it reduces the learning cost of related APIs, improves work efficiency, makes Java as elegant as a functional language, and makes the Java language "sweet". The tools and methods in Hutool come from each user's meticulous attention to detail. It covers all aspects of the underlying code of Java development. It is not only a sharp tool to solve small problems in large-scale project development, but also an efficiency responsibility in small-scale projects. Hutool is a friendly replacement for the "util" package in the project. It saves developers the time of encapsulating public classes and public tool methods in the project, allowing developers to focus on business while avoiding bugs caused by imperfect encapsulation to the greatest extent.
    Downloads: 7 This Week
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  • 4
    Java Tablesaw

    Java Tablesaw

    Java dataframe and visualization library

    Tablesaw is a dataframe and visualization library that supports loading, cleaning, transforming, filtering, and summarizing data. If you work with data in Java, it may save you time and effort. Tablesaw also supports descriptive statistics and can be used to prepare data for working with machine learning libraries like Smile, Tribuo, H20.ai, DL4J. Import data from RDBMS, Excel, CSV, TSV, JSON, HTML, or Fixed Width text files, whether they are local or remote (http, S3, etc.) Tablesaw supports data visualization by providing a wrapper for the Plot.ly JavaScript plotting library. Here are a few examples of the new library in action. Descriptive stats: mean, min, max, median, sum, product, standard deviation, variance, percentiles, geometric mean, skewness, kurtosis, etc. Add tablesaw-core to your project. You can find the version number for the latest release in the release notes.
    Downloads: 7 This Week
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  • Premier Construction Software Icon
    Premier Construction Software

    Premier is a global leader in financial construction ERP software.

    Rated #1 Construction Accounting Software by Forbes Advisor in 2022 & 2023. Our modern SAAS solution is designed to meet the needs of General Contractors, Developers/Owners, Homebuilders & Specialty Contractors.
    Learn More
  • 5
    Open HTML to PDF

    Open HTML to PDF

    An HTML to PDF library for the JVM

    Open HTML to PDF is a pure-Java library for rendering a reasonable subset of well-formed XML/XHTML (and even some HTML5) using CSS 2.1 (and later standards) for layout and formatting, outputting to PDF or images. Use this library to generated nice looking PDF documents. But be aware that you can not throw modern HTML5+ at this engine and expect a great result. You must special craft the HTML document for this library and use it's extended CSS feature like #31 or #32 to get good results. Avoid floats near page breaks and use table layouts.
    Downloads: 7 This Week
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  • 6
    Perl5 plugins for IntelliJ IDEA

    Perl5 plugins for IntelliJ IDEA

    Perl5 plugins for IntelliJ IDEA

    Perl5-IDEA is a plugin for JetBrains IDEs, including IntelliJ IDEA, that provides comprehensive support for Perl 5 development. It enhances the development experience with features like syntax highlighting, code completion, and debugging tools.​
    Downloads: 7 This Week
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  • 7
    RE2/J

    RE2/J

    linear time regular expression matching in Java

    RE2/J is a high-performance regular expression engine implemented in pure Java as a port of Google’s C++ RE2 library. Unlike traditional regex engines such as Java’s java.util.regex, PCRE, or Perl’s implementation—which rely on backtracking and can suffer from catastrophic exponential runtimes—RE2/J guarantees linear-time matching relative to input size. It achieves this efficiency by simulating all possible matches in a single pass using a nondeterministic finite automaton (NFA), ensuring predictable and safe performance even with complex patterns. This makes RE2/J ideal for applications that must handle user-supplied regular expressions securely without the risk of denial-of-service through regex backtracking. While it omits some advanced features like backreferences and certain Java regex options, it supports the vast majority of practical expressions used in production code. RE2/J thus provides a reliable, safe, and scalable alternative for developers.
    Downloads: 7 This Week
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  • 8
    RSocket

    RSocket

    Java implementation of RSocket

    Application protocol providing Reactive Streams semantics. RSocket provides a protocol for Reactive Streams semantics between client-server, and server-server communication. RSocket is a binary protocol for use on byte stream transports such as TCP, WebSockets, and Aeron. RSocket is intended to be consumed via one of the various implementation libraries which implement the RSocket Protocol. By default to make RSocket easier to use it copies the incoming Payload. Copying the payload comes at cost to performance and latency. If you want to use zero copy you must disable this. To disable copying you must include a payloadDecoder argument in your RSocketFactory. This will let you manage the Payload without copying the data from the underlying transport. You must free the Payload when you are done with them or you will get a memory leak. Used correctly this will reduce latency and increase performance.
    Downloads: 7 This Week
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  • 9
    Retrofit

    Retrofit

    Type-safe HTTP client for Android and Java by Square

    Retrofit is a type-safe HTTP client for Android and Java developed by Square. It allows developers to define REST API calls using simple interface annotations, automatically converting responses into Java objects using converters like Gson or Moshi. Retrofit greatly simplifies network requests by abstracting away boilerplate code, making API integration in mobile and Java apps seamless and maintainable.
    Downloads: 7 This Week
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  • Loan management software that makes it easy. Icon
    Loan management software that makes it easy.

    Ideal for lending professionals who are looking for a feature rich loan management system

    Bryt Software is ideal for lending professionals who are looking for a feature rich loan management system that is intuitive and easy to use. We are 100% cloud-based, software as a service. We believe in providing our customers with fair and honest pricing. Our monthly fees are based on your number of users and we have a minimal implementation charge.
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  • 10
    ScribeJava

    ScribeJava

    Simple OAuth library for Java

    Welcome to the home of ScribeJava, the simple OAuth client Java lib! That single line (added newlines for readability) is the only thing you need to configure ScribeJava with LinkedIn's OAuth API for example.
    Downloads: 7 This Week
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  • 11

    Tinker

    Android hot-fix solution library

    Tinker is a hot-fix solution library for Android, and the official one for WeChat. It supports dex, So library, and resources, allowing application updates without needing reinstallation. Tinker consists mainly of 3 parts: a gradle compile plugin, a core SDK library, and a command-line version of non-gradle compiled users. There are many other hot-fix solutions just like Tinker, but Tinker overcomes many of the problems that other solutions have. For starters, Tinker offers class, So and resource replacement, something that most other solutions do not. It offers full platform support and gradle support, while being smaller and simpler.
    Downloads: 7 This Week
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  • 12
    dnsjava

    dnsjava

    An implementation of the DNS protocol in Java

    dnsjava is an implementation of DNS in Java. It supports almost all defined record types (including the DNSSEC types), and unknown types. Can be used for queries, zone transfers, and dynamic updates. Includes a cache that can be used by clients, and an authoritative-only server. It supports TSIG authenticated messages, DNSSEC verification, and EDNS0.
    Downloads: 7 This Week
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  • 13
    Sesame

    Sesame

    Java RDF Framework

    This project is no longer actively maintained. It is succeeded by the Eclipse RDF4J project, which can be found at GitHub and at http://www.rdf4j.org/. Sesame is a de-facto standard framework for processing RDF data. This includes parsing, scalable storage, reasoning and full SPARQL 1.1 query/update support. Sesame offers a fully modular toolkit and an easy-to-use Java API that can be connected to all leading RDF storage solutions.
    Downloads: 31 This Week
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  • 14
    Event Ruler

    Event Ruler

    Java library that allows matching many thousands of Events per second

    Event Ruler (called Ruler in the rest of the doc for brevity) is a Java library that allows matching Rules to Events. An event is a list of fields, which may be given as name/value pairs or as a JSON object. A rule associates event field names with lists of possible values. Event Ruler is a Java library that allows matching many thousands of Events per second to any number of expressive and sophisticated rules.
    Downloads: 6 This Week
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  • 15
    JSqlParser

    JSqlParser

    JSqlParser parses an SQL statement and translate it into a hierarchy

    JSqlParser is a SQL statement parser. It translates SQLs in a traversable hierarchy of Java classes. JSqlParser is not limited to one database but provides support for a lot of specials of Oracle, SqlServer, MySQL, PostgreSQL. To name some, it has support for Oracles join syntax using (+), PostgreSQLs cast syntax using ::, relational operators like != and so on. Then the result can be accessed in a structured way. The generated Java class hierarchy can be navigated using the Visitor Pattern.
    Downloads: 6 This Week
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  • 16
    Kamon Telemetry

    Kamon Telemetry

    Distributed Tracing, Metrics and Context Propagation for applications

    Kamon Telemetry is a set of libraries for instrumenting applications running on the JVM. With Kamon Telemetry you can collect metrics, propagate context across threads and services, and get distributed traces automatically. The best way to get started is by following our installation guides and taking it from there. Have fun with Kamon. Monitor your backend applications, fix performance issues, and get alerted when problems happen. All without being a monitoring expert. Everybody starts monitoring with logs because they are there by default. Just connect to your server and start tailing. But logs have a hard time showing you the overall response times for your application, or whether certain calls to the database are happening in sequence or parallel (among a million other things).
    Downloads: 6 This Week
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  • 17
    OpenGL Canvas

    OpenGL Canvas

    An Android library that provides views using openGL canvas

    android-openGL-canvas is a lightweight OpenGL rendering library for Android that emulates the Android Canvas API using OpenGL ES 2.0. It’s designed for developers who want to achieve hardware-accelerated 2D graphics on Android while maintaining the familiar Canvas drawing commands. Ideal for real-time graphics, games, or custom views, this project provides a fast and flexible alternative to Android’s software rendering without the need for a full game engine. It bridges the gap between low-level graphics APIs and high-level UI rendering.
    Downloads: 6 This Week
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  • 18
    RoaringBitmap

    RoaringBitmap

    A better compressed bitset in Java

    Bitsets, also called bitmaps, are commonly used as fast data structures. Unfortunately, they can use too much memory. To compensate, we often use compressed bitmaps. Roaring bitmaps are compressed bitmaps which tend to outperform conventional compressed bitmaps such as WAH, EWAH or Concise. In some instances, roaring bitmaps can be hundreds of times faster and they often offer significantly better compression. They can even be faster than uncompressed bitmaps.
    Downloads: 6 This Week
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  • 19
    adventure

    adventure

    A user-interface library, formerly known as text, for Minecraft

    Adventure is a library for server-controllable user interface elements in Minecraft: Java Edition. The Adventure documentation should be used alongside the Javadocs. If you have further questions, feel free to join our Discord. Most users will want to use Adventure as a component of an existing modding platform. The best integrated are our Native Support, but we also support other platforms via adapters.
    Downloads: 6 This Week
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  • 20
    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: 156 This Week
    Last Update:
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  • 21
    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.
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    Downloads: 26 This Week
    Last Update:
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  • 22
    ConnectBot

    ConnectBot

    ConnectBot is the first SSH client for Android

    ConnectBot is a secure shell client for the Android platform. Its ultimate goal is to create a secure connection through which you can use a shell on a remote machine and transfer files back and forth to your phone. ConnectBot is a powerful open source SSH (Secure Shell) client. It can handle several simultaneous sessions, create secure connections in tunnel mode and allows Copy/Paste from other applications. This client allows you to connect to SSH (Secure Shell) servers that typically include UNIX-based servers.
    Downloads: 5 This Week
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  • 23
    Lightweight-Stream-API

    Lightweight-Stream-API

    Stream API from Java 8 rewritten on iterators for Java 7 and below

    Stream API from Java 8 rewritten on iterators for Java 7 and below.
    Downloads: 5 This Week
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  • 24
    Louvre

    Louvre

    A small customizable library useful to handle an image gallery

    A small customizable image picker. Useful to handle a gallery image pick action built-in your app.
    Downloads: 5 This Week
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  • 25

    Material Components for Android

    Modular and customizable Material Design UI components for Android

    Material Components for Android delivers Material Design’s popular and reliable design and development resources to Android developers. With Material Design’s modular and customizable UI components, Android developers can create beautiful, high quality products faster and easier. Developed by a core team of engineers and UX designers at Google, Material Components enable developers to achieve a more reliable development workflow for building exceptional and highly functional apps. Material Components for Android is a drop-in replacement for Android's Design Support Library, offering tried and trusted Material Design guidelines and components.
    Downloads: 5 This Week
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