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.

  • Full-stack observability with actually useful AI | Grafana Cloud Icon
    Full-stack observability with actually useful AI | Grafana Cloud

    Our generous forever free tier includes the full platform, including the AI Assistant, for 3 users with 10k metrics, 50GB logs, and 50GB traces.

    Built on open standards like Prometheus and OpenTelemetry, Grafana Cloud includes Kubernetes Monitoring, Application Observability, Incident Response, plus the AI-powered Grafana Assistant. Get started with our generous free tier today.
    Create free account
  • Go From AI Idea to AI App Fast Icon
    Go From AI Idea to AI App Fast

    One platform to build, fine-tune, and deploy ML models. No MLOps team required.

    Access Gemini 3 and 200+ models. Build chatbots, agents, or custom models with built-in monitoring and scaling.
    Try Free
  • 1
    OpenAPI Generator

    OpenAPI Generator

    OpenAPI Generator allows generation of API client libraries

    With 50+ client generators, you can easily generate code to interact with any server which exposes an OpenAPI document. Maintainers of APIs may also automatically generate and distribute clients as part of official SDKs. Each client supports different options and features, but all templates can be replaced with your own Mustache-based templates. Getting started with server development can be tough, especially if you're evaluating technologies. We can reduce the burden when you bring your own OpenAPI document. Some generators support Inversion of Control, allowing you to iterate on design via your OpenAPI document without worrying about blowing away your entire domain layer when you regenerate code. Ever wanted to iteratively design a MySQL database, but writing table declarations was too tedious? OpenAPI documents allow you to convert the metadata about your API into some other format.
    Downloads: 10 This Week
    Last Update:
    See Project
  • 2
    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: 9 This Week
    Last Update:
    See Project
  • 3
    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.
    Leader badge
    Downloads: 41 This Week
    Last Update:
    See Project
  • 4
    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: 8 This Week
    Last Update:
    See Project
  • Try Google Cloud Risk-Free With $300 in Credit Icon
    Try Google Cloud Risk-Free With $300 in Credit

    No hidden charges. No surprise bills. Cancel anytime.

    Use your credit across every product. Compute, storage, AI, analytics. When it runs out, 20+ products stay free. You only pay when you choose to.
    Start Free
  • 5
    HikariCP

    HikariCP

    A solid, high-performance, JDBC connection pool at last

    HikariCP is a high-performance JDBC connection pooling library designed to offer minimal overhead and maximum throughput. It aims for simplicity and stability, concentrating on fast connection acquisition and minimal latency under load. Its internals manage a pool of connections aggressively but smartly, with options such as leak detection, timeout thresholds, and adaptive connection retirement. Because it avoids heavy internal locking, it scales well in high-concurrency environments, making it a popular choice in microservices and high-throughput web backends. Metrics and instrumentation hooks (for example, via Dropwizard or Micrometer) allow runtime visibility into pool usage and health. HikariCP’s focus is on doing the essential work of pooling correctly and efficiently, rather than bundling extraneous features.
    Downloads: 8 This Week
    Last Update:
    See Project
  • 6
    International Components for Unicode

    International Components for Unicode

    The home of the ICU project source code

    ICU is a mature, widely used set of C/C++ and Java libraries providing Unicode and Globalization support for software applications. ICU is widely portable and gives applications the same results on all platforms and between C/C++ and Java software. ICU is released under a nonrestrictive open-source license that is suitable for use with both commercial software and with other open-source or free software. Convert text data to or from Unicode and nearly any other character set or encoding. ICU's conversion tables are based on charset data collected by IBM over the course of many decades and is the most complete available anywhere. Compare strings according to the conventions and standards of a particular language, region or country. ICU's collation is based on the Unicode Collation Algorithm plus locale-specific comparison rules from the Common Locale Data Repository, a comprehensive source for this type of data.
    Downloads: 8 This Week
    Last Update:
    See Project
  • 7
    Jackcess
    A pure Java library for reading from and writing to MS Access databases.
    Leader badge
    Downloads: 36 This Week
    Last Update:
    See Project
  • 8
    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.
    Leader badge
    Downloads: 53 This Week
    Last Update:
    See Project
  • 9
    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: 7 This Week
    Last Update:
    See Project
  • MongoDB Atlas runs apps anywhere Icon
    MongoDB Atlas runs apps anywhere

    Deploy in 115+ regions with the modern database for every enterprise.

    MongoDB Atlas gives you the freedom to build and run modern applications anywhere—across AWS, Azure, and Google Cloud. With global availability in over 115 regions, Atlas lets you deploy close to your users, meet compliance needs, and scale with confidence across any geography.
    Start Free
  • 10
    Javassist

    Javassist

    Java bytecode engineering toolkit

    Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java; it enables Java programs to define a new class at runtime and to modify a class file when the JVM loads it. Unlike other similar bytecode editors, Javassist provides two levels of API: source level and bytecode level. If the users use the source- level API, they can edit a class file without knowledge of the specifications of the Java bytecode. The whole API is designed with only the vocabulary of the Java language. You can even specify inserted bytecode in the form of source text; Javassist compiles it on the fly. On the other hand, the bytecode-level API allows the users to directly edit a class file as other editors.
    Downloads: 7 This Week
    Last Update:
    See Project
  • 11
    red5-server

    red5-server

    Red5 Server core

    Red5 is an Open Source Flash Server written in Java that supports streaming Video (FLV, F4V, MP4, 3GP). Streaming Audio (MP3, F4A, M4A, AAC) Recording Client Streams (FLV and AVC+AAC in FLV container) Shared objects, live stream publishing, remoting, and protocols: RTMP, RTMPT, RTMPS, and RTMPE.
    Downloads: 7 This Week
    Last Update:
    See Project
  • 12
    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.
    Leader badge
    Downloads: 34 This Week
    Last Update:
    See Project
  • 13
    Importer library to import assets from different common 3D file formats such as Collada, Blend, Obj, X, 3DS, LWO, MD5, MD2, MD3, MDL, MS3D and a lot of other formats. The data is stored in an own in-memory data-format, which can be easily processed. www.open3mod.com/ is a 3D model viewer and exporter based on Assimp that is also Open Source.
    Downloads: 27 This Week
    Last Update:
    See Project
  • 14
    FFmpeg-Android-Java

    FFmpeg-Android-Java

    Android java library for FFmpeg binary

    FFmpeg Android java is a java library that simplifies your task of using ffmpeg in Android project which I've compiled using FFmpeg-Android.
    Downloads: 6 This Week
    Last Update:
    See Project
  • 15
    JMX Exporter

    JMX Exporter

    A process for exposing JMX Beans via HTTP for Prometheus consumption

    JMX to Prometheus exporter: a collector that can configurable scrape and expose mBeans of a JMX target. This exporter is intended to be run as a Java Agent, exposing a HTTP server and serving metrics of the local JVM. It can be also run as a standalone HTTP server and scrape remote JMX targets, but this has various disadvantages, such as being harder to configure and being unable to expose process metrics (e.g., memory and CPU usage). Running the exporter as a Java agent is strongly encouraged.
    Downloads: 6 This Week
    Last Update:
    See Project
  • 16
    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: 6 This Week
    Last Update:
    See Project
  • 17
    QR Code generator library

    QR Code generator library

    High-quality QR Code generator library in Java, TypeScript/JavaScript

    This project aims to be the best, clearest library for generating QR Codes. My primary goals are flexible options and absolute correctness. The secondary goals are compact implementation size and good documentation comments. This work is an independent implementation based on reading the official ISO specification documents. I believe that my library has a more intuitive API and shorter code length than competing libraries out there. The library is designed first in Java and then ported to TypeScript, Python, Rust, C++, and C. It is open source under the MIT License. For each language, the codebase is roughly 1000 lines of code and has no dependencies other than the respective language’s standard library.
    Downloads: 6 This Week
    Last Update:
    See Project
  • 18

    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.
    Leader badge
    Downloads: 38 This Week
    Last Update:
    See Project
  • 19
    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/.
    Leader badge
    Downloads: 147 This Week
    Last Update:
    See Project
  • 20
    BIMserver

    BIMserver

    The open source BIMserver platform

    The Building Information Model server (short: BIMserver) enables you to store and manage the information of a construction (or other building related) project. Data is stored in the open data standard IFC. The BIMserver is not a fileserver, but it uses a model-driven architecture approach. This means that IFC data is stored as objects. You could see BIMserver as an IFC database, with special extra features like model checking, versioning, project structures, merging, etc. The main advantage of this approach is the ability to query, merge and filter the BIM model and generate IFC output (i.e. files) on the fly. Thanks to its multi-user support, multiple people can work on their own part of the dataset, while the complete dataset is updated on the fly. Other users can get notifications when the model (or a part of it) is updated.
    Downloads: 5 This Week
    Last Update:
    See Project
  • 21
    Logbook

    Logbook

    An extensible Java library for HTTP request and response logging

    Logbook is an extensible Java library to enable complete request and response logging for different client- and server-side technologies. It satisfies a special need by a) allowing web application developers to log any HTTP traffic that an application receives or sends b) in a way that makes it easy to persist and analyze it later. This can be useful for traditional log analysis, meeting audit requirements or investigating individual historic traffic issues. Logbook is ready to use out of the box for most common setups. Even for uncommon applications and technologies, it should be simple to implement the necessary interfaces to connect a library/framework/etc. to it.
    Downloads: 5 This Week
    Last Update:
    See Project
  • 22
    MPAndroidChart

    MPAndroidChart

    A powerful Android chart view / graph view library

    MPAndroidChart is a powerful chart library for Android that offers a beautiful and comprehensive range of charts and graphs. Powerful and very easy to use, it supports the creation of bar-, line-, pie-, bubble-, scatter-, radar- and candlestick charts, as well as scaling, dragging and animations. Charts are rendered cleanly and are visually engaging. Visualizing your data exactly how you want is so much easier with MPAndroidChart. To see more great examples of MPAndroidChart, download the MPAndroidChart Example App on Google Play.
    Downloads: 5 This Week
    Last Update:
    See Project
  • 23
    Micrometer

    Micrometer

    App observability facade for the most popular observability tools

    Micrometer provides a simple facade over the instrumentation clients for the most popular observability systems, allowing you to instrument your JVM-based application code without vendor lock-in. Think SLF4J, but for observability. Micrometer provides vendor-neutral interfaces for timers, gauges, counters, distribution summaries, and long task timers with a dimensional data model that, when paired with a dimensional monitoring system, allows for efficient access to a particular named metric with the ability to drill down across its dimensions. Out-of-the-box instrumentation of caches, the class loader, garbage collection, processor utilization, thread pools, and more tailored to actionable insight. Micrometer is the instrumentation library powering the delivery of application observability from Spring Boot applications.
    Downloads: 5 This Week
    Last Update:
    See Project
  • 24
    Pinot

    Pinot

    Apache Pinot - A realtime distributed OLAP datastore

    Realtime distributed OLAP datastore, designed to answer OLAP queries with low latency. Pinot is designed to answer OLAP queries with low latency on immutable data and mutable data(Upsert Support) Pluggable indexing technologies - Sorted Index, Bitmap Index, Inverted Index, StarTree Index, Bloom Filter, Range Index, Text Search Index(Lucence/FST), Json Index, Geospatial Index. Near Realtime ingestion with Apache Kafka, Apache Pulsar, Kinesissupports JSON, Avro, ProtoBuf, Thrift formats. Apache Pinot supports dimension lookup joins currently. Full SQL join support in Apache Pinot is coming soon. In the interim, full SQL joins can be performed by querying Pinot via the Trino or PrestoDB connector. Apache Pinot provides SQL interface for querying interactively, as well as programmatically via rest-api.
    Downloads: 5 This Week
    Last Update:
    See Project
  • 25
    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
    Last Update:
    See Project
MongoDB Logo MongoDB