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.

  • Skillfully - The future of skills based hiring Icon
    Skillfully - The future of skills based hiring

    Realistic Workplace Simulations that Show Applicant Skills in Action

    Skillfully transforms hiring through AI-powered skill simulations that show you how candidates actually perform before you hire them. Our platform helps companies cut through AI-generated resumes and rehearsed interviews by validating real capabilities in action. Through dynamic job specific simulations and skill-based assessments, companies like Bloomberg and McKinsey have cut screening time by 50% while dramatically improving hire quality.
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  • The Most Powerful Software Platform for EHSQ and ESG Management Icon
    The Most Powerful Software Platform for EHSQ and ESG Management

    Addresses the needs of small businesses and large global organizations with thousands of users in multiple locations.

    Choose from a complete set of software solutions across EHSQ that address all aspects of top performing Environmental, Health and Safety, and Quality management programs.
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  • 1
    OpenAI-Java

    OpenAI-Java

    OpenAI Api Client in Java

    OpenAI-Java is the official Java client library provided by OpenAI for interacting with the OpenAI API. It is designed to make it easier for Java applications to call endpoints like chat completions, embeddings, function calling, streaming, and other model services using idiomatic Java patterns. You configure the client (often via environment variables or system properties), then build parameter objects (e.g. ChatCompletionCreateParams) and invoke methods like client.chat().completions().create(...) to send requests in a type-safe way. The library also supports streaming APIs, where the response arrives in chunks, using helpers like ChatCompletionAccumulator to accumulate partial responses into a full object. For complex use cases (e.g. structured outputs, function calling), it provides schema support, JSON annotations, and schema validation.
    Downloads: 3 This Week
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  • 2
    RoundCornerProgressBar

    RoundCornerProgressBar

    [Android] Round Corner Progress Bar Library for Android

    Round corner is cool. Let's make your progress bar with round corner. Colorful rounded corner progress bar.
    Downloads: 3 This Week
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  • 3
    SOFAJRaft

    SOFAJRaft

    A production-grade java implementation of RAFT consensus algorithm

    SOFAJRaft is a production-level, high-performance Java implementation based on the RAFT consistency algorithm that supports MULTI-RAFT-GROUP for high-load, low-latency scenarios. With SOFAJRaft you can focus on your business area. SOFAJRaft handles all RAFT-related technical challenges. SOFAJRaft is very user-friendly, which provides several examples, making it easy to understand and use.
    Downloads: 3 This Week
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  • 4
    Siddhi Core Libraries

    Siddhi Core Libraries

    Stream Processing and Complex Event Processing Engine

    Fully open source, cloud-native, scalable, micro streaming, and complex event processing system capable of building event-driven applications for use cases such as real-time analytics, data integration, notification management, and adaptive decision-making. Event processing logic can be written using Streaming SQL queries via graphical and source editors, to capture events from diverse data sources, process and analyze them, integrate with multiple services and data stores, and publish output to various endpoints in real time. Agile development experience with SQL-like query language and graphical drag-and-drop editor supporting event simulation. Lightweight runtime that can natively run on Kubernetes, Docker, VM, or bare metal, and embedded in any Java or Python application. Scalable, and highly available distributed event processing on Kubernetes, with NATS Streaming and Siddhi Kubernetes Operator.
    Downloads: 3 This Week
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  • Intelligent Retail Management Icon
    Intelligent Retail Management

    Retail space, product categories, planograms, automatic ordering, and shelf labels management

    Quant offers a wide range of solutions for retail. Within one integrated software system, it allows you to efficiently combine the management of retail space, shelf labels and marketing materials with task management, reporting and automatic replenishment.
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  • 5
    springdoc-openapi

    springdoc-openapi

    Library for OpenAPI 3 with spring-boot

    An extended support for springdoc-openapi v1 project is now available for organizations that need support beyond 2023. The springdoc-openapi Java library helps automating the generation of API documentation using Spring Boot projects. springdoc-openapi works by examining an application at runtime to infer API semantics based on Spring configurations, class structure and various annotations. The library automatically generates documentation in JSON/YAML and HTML formatted pages. The generated documentation can be complemented using swagger-api annotations.
    Downloads: 3 This Week
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  • 6

    eBus

    Publish/Subscribe, Request/Reply Messaging API for Java.

    A Java middleware API supporting broker-less, type+topic-based publish/subscribe and request/reply messaging for both intra- and inter-application, object-level communication. Broker-less: messages are transmitted directly between eBus applications. There is no message broker (i.e. server) in between. Type+topic addressing: eBus clients subscribe to a message class (type) and message topic, providing stronger typing than just topic-based subscriptions. Object-level communication: eBus delivers messages directly to client objects, not to a client process.
    Downloads: 44 This Week
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  • 7
    CSSBox

    CSSBox

    Pure Java HTML / CSS rendering engine

    CSSBox is an (X)HTML/CSS rendering engine written in pure Java. Its primary purpose is to provide a complete information about the rendered page suitable for further processing. However, it also allows displaying the rendered document.
    Downloads: 19 This Week
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  • 8
    Aleph

    Aleph

    Asynchronous streaming communication for Clojure

    Aleph is an asynchronous I/O framework for Clojure built atop Netty, offering efficient, non-blocking network programming with support for HTTP, raw TCP/UDP, and streaming through Manifold streams. Aleph follows the Ring spec fully and can be a drop-in replacement for any existing Ring-compliant server. However, it also allows for the handler function to return a Manifold deferred to represent an eventual response. This feature may not play nicely with synchronous Ring middleware, which modifies the response, but this can be easily fixed by reimplementing the middleware using Manifold's let-flow operator. The aleph.http/wrap-ring-async-handler helper can be used to convert async 3-arity Ring handler to an Aleph-compliant one.
    Downloads: 2 This Week
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  • 9
    DSL-JSON library

    DSL-JSON library

    High performance JVM JSON library

    Fastest JVM (Java/Android/Scala/Kotlin) JSON library with advanced compile-time data binding support. Java JSON library designed for performance. Originally built for invasive software composition with DSL Platform compiler. v1 core library was targeting Java6, while v2 targets Java8. So there is no need anymore for dsl-json-java8 project and instead, just dsl-json project should be referenced. From v2 only a single annotation processor is supported, which was previously in the java8 project. Joda and some other specific libraries were removed. If you still need converters for those types, you need to include them in your project.
    Downloads: 2 This Week
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  • Intelligent Automation Solutions Built for Modern Finance Teams Icon
    Intelligent Automation Solutions Built for Modern Finance Teams

    We do CFO stuff.

    Digitally transform your business with workflow automation and integrated payment solutions. Digitally store and secure your data with advanced search and accessibility features that keeps your documents at the tip of your team’s fingers.
    Learn More
  • 10
    ENViews

    ENViews

    A cool dynamic view library

    ENViews is an Android UI library focused on delivering visually rich and dynamic animated components inspired by modern design concepts. It provides a collection of custom views that emphasize motion and interaction, including elements such as loading indicators, play buttons, search animations, and refresh effects. The library is based on design work by Nick Buturishvili, translating high-quality motion design concepts into reusable Android components. Its primary purpose is to enhance user experience by adding smooth, engaging animations that go beyond standard Android UI elements. ENViews is implemented in Java and integrates into Android projects via Gradle, making it easy to include in existing mobile applications. The library includes a demo project that showcases how each animated component behaves and how it can be implemented in real scenarios.
    Downloads: 2 This Week
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  • 11
    Instacapture 2.0

    Instacapture 2.0

    Android library to capture screenshot from your app

    Android library to capture screenshots from your app.
    Downloads: 2 This Week
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  • 12
    LaTeX Examples

    LaTeX Examples

    Examples for the usage of LaTeX

    LaTeX-examples is a repository collecting a variety of example documents and snippets demonstrating LaTeX features, usage patterns, and common templates. It acts as a playground for learning LaTeX syntax, macros, formatting tricks, and document structuring practices. Files include sample articles, reports, book chapters, presentations (using Beamer), tables, mathematical typesetting examples (equations, aligned systems, integrals, matrices), custom macros, and styling. The project is useful both for beginners who want to see working LaTeX samples and for more advanced users seeking snippets for specific formatting needs (e.g., customizing headers, floats, customizing theorem environments). Because examples are self-contained and well-commented, users can copy, adapt, or test them without needing a large TeX toolchain.
    Downloads: 2 This Week
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  • 13
    Let

    Let

    Annotation based API flavored with AOP to handle Android models

    Annotation-based simple API flavored with AOP to handle new Android runtime permission model. If you check Google's Samples about the new permission model, you'll see a lot of boilerplate code for requesting, handling, and retrying the request for required permissions. Let will minimize the boilerplate code you have to write for requesting and handling permissions and hence help you keep your code more readable. Let will check these annotated methods and execute them unless the permissions required are granted; otherwise, Let will put on hold the method execution on and request these permissions at runtime. After examining the permission request result, Let will execute the method already put on hold only if the permissions are granted by user.
    Downloads: 2 This Week
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  • 14
    Socket.IO-client Java

    Socket.IO-client Java

    A Socket.IO client library for Java

    This is the Socket.IO Client Library for Java, which is simply ported from the JavaScript client. The latest artifact is available on Maven Central. There are several ways to handle events that are transmitted between the server and the client. Add the listener function to the end of the listeners array for the event named eventName. Add a one-time listener function for the event named eventName. Remove the specified listener from the listener array for the event named eventName. Remove all listeners for the specific eventName. Remove all listeners (for any event). Besides emitting and listening to events, the Socket instance has a few attributes that may be of use in your application. Each new connection is assigned a random 20-characters identifier.
    Downloads: 2 This Week
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  • 15
    Valkey GLIDE

    Valkey GLIDE

    An open source Valkey client library that supports Valkey and Redis

    Valkey General Language Independent Driver for the Enterprise (GLIDE), is an open-source Valkey client library. Valkey GLIDE is one of the official client libraries for Valkey, and it supports all Valkey commands. Valkey GLIDE supports Valkey 7.2 and above, and Redis open-source 6.2, 7.0 and 7.2. Application programmers use Valkey GLIDE to safely and reliably connect their applications to Valkey- and Redis OSS- compatible services. Valkey GLIDE is designed for reliability, optimized performance, and high-availability, for Valkey and Redis OSS-based applications. It is sponsored and supported by AWS, and is pre-configured with best practices learned from over a decade of operating Redis OSS-compatible services used by hundreds of thousands of customers. To help ensure consistency in application development and operations, Valkey GLIDE is implemented using a core driver framework, written in Rust, with language-specific extensions.
    Downloads: 2 This Week
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  • 16
    fastjson

    fastjson

    A fast JSON parser/generator for Java

    Fastjson is a Java library that can be used to quickly convert Java Objects into their JSON representation or convert JSON strings to their equivalent Java object. Based on benchmarks it provides the best performance in both server side and Android client, and can work with arbitrary Java objects, even those pre-existing objects of which you do not have the source code. Fastjson provides a simple conversion method to turn Java objects to JSON and vice versa, with extensive support of Java Generics and arbitrarily complex objects.
    Downloads: 2 This Week
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  • 17
    react-native-geolocation

    react-native-geolocation

    Geolocation APIs for React Native

    The Geolocation API module for React Native extends the Geolocation web spec.
    Downloads: 2 This Week
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  • 18

    UnboundID LDAP SDK for Java

    A Java-based LDAP API

    A fast, comprehensive, and easy-to-use Java API for communicating with LDAP directory servers and performing related tasks like reading and writing LDIF, encoding and decoding data using base64 and ASN.1 BER, and performing secure communication.
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    Downloads: 10 This Week
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  • 19

    JEditor

    a simple Java text Editor with syntax highlighting which is designed t

    JEditor is a simple Java text Editor with syntax highlighting which is designed to be used in a library in other applications. A typical use case is an application which needs to edit text files.
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    Downloads: 26 This Week
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  • 20
    A library help for signing data with PKCS11 token (certificates with SHA1withRSA Sign Algorithm) and create CMS packages. It uses Bouncy Castle Crypto API and SUNPKCS11. Also it verify the signed data and verify signing certificate's OCSP control.
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    Downloads: 41 This Week
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  • 21
    Moved to https://github.com/DANS-KNAW/dans-dbf-lib.
    Downloads: 12 This Week
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  • 22
    JChart2D

    JChart2D

    jchart2d is a real-time charting library written in java.

    JChart2D is a easy to use component for displaying two- dimensional traces in a coordinate system written in Java. It supports real-time (animated) charting, custom trace rendering, Multithreading, viewports, automatic scaling and labels. Former UI controls (right click context menu, file menu) have been ported to the subproject jchart2d-uimenu (https://sourceforge.net/projects/jchart2d-uimenu.jchart2d.p/) for the benefit of having no dependencies to 3rd party libraries.
    Downloads: 6 This Week
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  • 23
    PDFReporter

    PDFReporter

    Generating documents and reports, offline enabled and reliable.

    The library is a fork of the popular open source Jasper Reports and supports the common features provided by Jasper Reports, but offline and for mobile apps. The PDFReporter library supports iOS, Java and Android library. For your document and report design you use the PDFReporter Studio where you can visualize your data. If you want to use the library commercially please visit our official webpage.
    Downloads: 9 This Week
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  • 24
    Java Curses Library

    Java Curses Library

    JCurses, a java console windowing toolkit for Windows and Linux

    The Java Curses Library (JCurses) is a library for developing text terminal based applications using Java programming language. It is implemented as a Windowing toolkit similar to AWT, but built upon the UNIX "curses" windowing system.
    Downloads: 8 This Week
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  • 25
    Android Hidden APIs

    Android Hidden APIs

    A library that provides access to Android hidden APIs

    Android Hidden APIs are classes, methods, and resources that Google hides from you because of stability reasons. These features are hidden because they may be changed on next API version. The internal APIs are located in package com.android.internal and available in the framework.jar, while the hidden APIs are located in the android.jar file with @hide javadoc attribute. Now you know the difference. But I will refer to both as hidden APIs. This repo contains a custom android.jar which you can use to develop your app.
    Downloads: 1 This Week
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