Java

Popular secure object-oriented language designed for flexibility to "write once, run anywhere".

811 resources2 categoriesView Original

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ActiveJ

Lightweight asynchronous framework built from the ground up for developing high-performance web applications.

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ActiveRPC

Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions.

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Adopt Open JDK

Community-driven OpenJDK builds, including both HotSpot and OpenJ9.

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ADT4J

JSR-269 code generator for algebraic data types.

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Aeron

Efficient, reliable, unicast and multicast message transport.

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Agrona

Data structures and utility methods that are common in high-performance applications.

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Airline

Annotation-based framework for parsing Git-like command-line arguments.

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Akka

Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.

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ANTLR

Complex full-featured framework for top-down parsing.

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Apache ActiveMQ

Message broker that implements JMS and converts synchronous to asynchronous communication.

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Apache Avro

Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.

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Apache Calcite

Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.

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Apache Camel

Glues together different transport APIs via Enterprise Integration Patterns.

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Apache Cayenne

Provides a clean, static API for data access. Also includes a GUI Modeler for working with database mappings, and DB reverse engineering and generation.

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Apache DeltaSpike

CDI extension framework.

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Apache Drill

Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration.

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Apache Flink

Fast, reliable, large-scale data processing engine.

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Apache FOP

Creates PDFs from XSL-FO.

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Apache Geode

In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.

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Apache HttpComponents

Toolset of low-level Java components focused on HTTP and associated protocols.

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Apache JMeter

Functional testing and performance measurements.

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Apache Kafka

High-throughput distributed messaging system.

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Apache Log4j 2

Complete rewrite with a powerful plugin and configuration architecture.

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Apache Lucene

High-performance, full-featured, cross-platform, text search engine library.

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Apache Mahout

Scalable algorithms focused on collaborative filtering, clustering and classification.

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Apache Maven

Declarative build and dependency management that favors convention over configuration. It might be preferable to Apache Ant, which uses a rather procedural approach and can be difficult to maintain.

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Apache Nutch

Highly extensible, highly scalable web crawler for production environments.

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Apache Orc

Fast and efficient columnar storage format for Hadoop-based workloads.

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Apache Parquet

Columnar storage format based on assembly algorithms from Google's paper on Dremel.

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Apache PDFBox

Toolbox for creating and manipulating PDFs.

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Apache Phoenix

High-performance relational database layer over HBase for low-latency applications.

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Apache POI

Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT).

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Apache Pulsar

Distributed pub/sub-messaging system.

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Apache Qpid

Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms.

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Apache RocketMQ

Fast, reliable, and scalable distributed messaging platform.

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Apache Shiro

Performs authentication, authorization, cryptography and session management.

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Apache SIS

Library for developing geospatial applications.

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Apache Solr

Enterprise search engine optimized for high-volume traffic.

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Apache Storm

Realtime computation system.

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Apache Tapestry

Component-oriented framework for creating dynamic, robust, highly scalable web applications.

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Apache Thrift

Data interchange format that originated at Facebook.

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Apache Tomcat

Robust, all-round server for Servlet and JSP.

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Apache TomEE

Tomcat plus Java EE.

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Apache Wicket

Component-based web application framework similar to Tapestry, with a stateful GUI.

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Apache ZooKeeper

Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.

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Aparapi

Converts bytecode to OpenCL which allows execution on GPUs.

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Apitally

Simple, privacy-focused API monitoring, analytics and request logging for Spring Boot apps.

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ArangoDB

ArangoDB Java driver.

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ArchUnit

Test library for specifying and asserting architecture rules.

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Armeria

Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.

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Arquillian

Integration and functional testing platform for Java EE containers.

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Arthas

Allows to troubleshoot production issues for applications without modifying code or restarting servers.

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Artipie

Binary artifact management toolkit which hosts them on the file system or S3.

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ASM

All-purpose, low-level bytecode manipulation and analysis.

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AspectJ

Seamless aspect-oriented programming extension.

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AssertJ

Fluent assertions that improve readability.

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Async Http Client

Asynchronous HTTP and WebSocket client library.

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Atomikos

Provides transactions for REST, SOA and microservices with support for JTA and XA.

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Atomix

Fault-tolerant distributed coordination framework.

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Auto

Generates factory, service, and value classes.

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Automon

Combines the power of AOP with monitoring and/or logging tools.

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AutoMQ

AutoMQ is a cloud-native, serverless reinvented Kafka that is easily scalable, manage-less and cost-effective.

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AutoParams

Supports generating test data or combining scenarios for parameterized tests.

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avaje config

Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners.

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Avaje Http Client

Wrapper on JDK 11's HttpClient that adds Feign-like interface among other enhancements.

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Avaje Http Server

Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE.

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Avaje Inject

Microservice-focused compile-time injection framework without reflection.

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Avaje Jsonb

Reflection-free Json binding via source code generation with Jackson-like annotations.

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Awaitility

DSL for synchronizing asynchronous operations.

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AWS SDK for Java

Provides Java APIs for interacting with Amazon Web Services.

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Axon

Framework for creating CQRS applications.

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Bazel

Tool from Google that builds code quickly and reliably.

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BCEL

Byte Code Engineering Library - analyze, create, and manipulate Java class files.

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Beanmother

Sets up beans from YAML fixtures.

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BeanUtils

Easy-to-use wrappers around the Java reflection and introspection APIs.

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BeanUtils2

Redesign of Commons BeanUtils.

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Big Queue

Fast and persistent queue based on memory-mapped files.

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BioJava

Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.

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Bitronix

Simple but complete implementation of the JTA 1.1 API.

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Blade

Lightweight, modular framework that aims to be elegant and simple.

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BoofCV

Library for image processing, camera calibration, tracking, SFM, MVS, 3D vision, QR Code and much more.

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Bootique

Minimally opinionated framework for runnable apps.

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Bouncy Castle

All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.

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BSF

Bean Scripting Framework - interface to scripting languages, including JSR-223.

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Buck2

Encourages the creation of small, reusable modules consisting of code and resources.

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bucket4j

Rate limiting library based on token-bucket algorithm.

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Byte Buddy

Further simplifies bytecode generation with a fluent API.

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bytecode-viewer

Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)

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Byteman

Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting. (LGPL-2.1-or-later)

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cache2k

In-memory high performance caching library.

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cactoos

Collection of object-oriented primitives.

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Cadence

Stateful code platform from Uber.

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Caffeine

High-performance, near-optimal caching library.

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Capsule

Simple and powerful packaging and deployment. A fat JAR on steroids, or a "Docker for Java" that supports JVM-optimized containers.

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Cassandre

Trading bot framework.

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CATG

Concolic unit testing engine. Automatically generates unit tests using formal methods.

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cdi-test

JUnit extension for easy and efficient testing of CDI components.

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Central Repository

Largest binary component repository available as a free service to the open-source community. Default used by Apache Maven, and available in all other build tools.

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centraldogma

Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.

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cglib

Bytecode generation library.

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ch.vorburger.exec

Convenient API around Apache Commons Exec.

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Chain

Chain of Responsibility pattern implementation.

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Chart-FX

Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.

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Checker Framework

Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)

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Checkstyle

Static analysis of coding conventions and standards. (LGPL-2.1-or-later)

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Choco

Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.

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Chocotea

Generates postman collection, environment and integration tests from java code.

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Chronicle Map

Efficient, in-memory (opt. persisted to disk), off-heap key-value store.

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Citrus

Integration testing framework that focuses on both client- and server-side messaging.

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ClassGraph

ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.

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ClassScan

Find Class interfaces, methods, fields, and annotations without loading.

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CLI

Command-line arguments parser.

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CLI2

Redesign of Commons CLI.

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Clover

Relies on source-code instrumentation instead of bytecode instrumentation.

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Cobertura

Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)

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Codec

General encoding/decoding algorithms, e.g. phonetic, base64 or URL.

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Codename One

Cross-platform solution for writing native mobile apps. (GPL-2.0-only WITH Classpath-exception-2.0)

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CogCompNLP

Provides common annotators for plain text input. (Research and Academic Use License)

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Collections

Extends or augments the Java Collections Framework.

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Commons-networking

Client for server-sent events (SSE).

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Compress

Defines an API for working with tar, zip and bzip2 files.

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Comsat

Integrates standard Java web-related APIs with Quasar fibers and actors.

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ConcurrentUnit

Toolkit for testing multi-threaded and asynchronous applications.

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config

Configuration library supporting Java properties, JSON or its human optimized superset HOCON.

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Configurate

Configuration library with support for various configuration formats and transformations.

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Configuration

Reading of configuration/preferences files in various formats.

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ConsoleCaptor

Captures console output for unit testing purposes.

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consul-api

Client for the Consul API: a distributed, highly available and datacenter-aware registry/discovery service.

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Convert

Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.

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CoreNLP

Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)

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Corretto

No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)

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CosId

Universal, flexible, high-performance distributed ID generator.

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CQEngine

Ultra-fast, SQL-like queries on Java collections.

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CRaSH

Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others. (LGPL-2.1-or-later)

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Crawler4j

Simple and lightweight web crawler.

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Crnk

Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.

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Cryptomator

Multiplatform, transparent, client-side encryption of files in the cloud. (GPL-3.0-only)

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CSV

Component for reading and writing comma separated value files.

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CUBA Platform

High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.

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Cucumber

Provides a way to describe features in a plain language which customers can understand.

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Cukes-REST

Collection of Gherkin steps for REST-service testing using Cucumber.

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Curator Framework

High-level API for Apache ZooKeeper.

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Cyclops

Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.

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Daemon

Alternative invocation mechanism for unix-daemon-like java code.

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Dagger

Compile-time injection framework without reflection.

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Daikon

Detects likely program invariants and generates JML specs based on those invariants.

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Datafaker

Modern fake data generator forked from Java Faker.

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DataMelt

Environment for scientific computation, data analysis and data visualization. (GPL-3.0-or-later)

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DatumBox

Provides several algorithms and pre-trained models for natural language processing.

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db-scheduler

Persistent and cluster-friendly scheduler.

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DBCP

Database connection pooling services.

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DbUtils

JDBC helper library.

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DCEVM

JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)

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Debezium

Low latency data streaming platform for change data capture.

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Deeplearning4j

Distributed and multi-threaded deep learning library.

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Deezpatch

Simple, lightweight, and performant dispatch library for decoupling messages (requests and events) and message handlers.

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DependencyCheck

Detects publicly disclosed vulnerabilities contained within a project's dependencies.

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derive4j

Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)

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Design Patterns

Implementation and explanation of the most common design patterns.

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Dex

Java/JavaFX tool capable of powerful ETL and data visualization.

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Digester

XML-to-Java-object mapping utility.

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Disruptor

Inter-thread messaging library.

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DJL

High-level and engine-agnostic framework for deep learning.

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DKPro

Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.

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documents4j

API for document format conversion using third-party converters such as MS Word.

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docx4j

Create and manipulate Microsoft Open XML files.

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Doma

Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.

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dOOv

Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.

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dotenv

Twelve-factor configuration library which uses environment-specific files.

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Dragonwell8

Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.

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dregex

Regular expression engine that uses deterministic finite automata. It supports some Perl-style features and yet retains linear matching time, and also offers set operations.

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Drift

Easy-to-use, annotation-based library for creating Thrift clients and serializable types.

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Dropwizard

Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.

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Dropwizard Circuit Breaker

Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)

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Dropwizard Metrics

Expose metrics via JMX or HTTP and send them to a database.

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druid

High-performance, column-oriented, distributed data store.

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DSL-JSON

JSON library with advanced compile time databinding.

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Dubbo

High-performance RPC framework.

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Dynamic Jasper

Abstraction layer to JasperReports. (LGPL-3.0-only)

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DynamicReports

Simplifies JasperReports. (LGPL-3.0-only)

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easy-batch

Set up batch jobs with simple processing pipelines. Records are read in sequence from a data source, processed in pipeline and written in batches to a data sink.

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EasyMock

EasyMock is a Java library that provides an easy way to use Mock Objects in unit testing.

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Ebean

Provides simple and fast data access.

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Echopraxia

API designed around structured logging, rich context, and conditional logging. There are Logback and Log4J2 implementations, but Echopraxia's API is completely dependency-free, meaning it can be implemented with any logging API.

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Eclipse

Established open-source project with support for lots of plugins and languages.

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Eclipse BIRT

Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor.

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Eclipse Collections

Collections framework inspired by Smalltalk.

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EclipseLink

Supports a number of persistence standards: JPA, JAXB, JCA and SDO.

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Ehcache

Distributed general-purpose cache.

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Elasticsearch

Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.

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Elide

Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.

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Email

Library for sending e-mail from Java.

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Embulk

Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.

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Erdos

Modular, light and easy graph framework for theoretic algorithms.

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Error Prone

Catches common programming mistakes as compile-time errors.

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Error Prone Support

Error Prone extensions: extra bug checkers and a large battery of Refaster templates.

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Eureka

REST-based service registry for resilient load balancing and failover.

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EventBus

Simple publish/subscribe event bus.

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Exec

API for dealing with external process execution and environment management in Java.

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eXist

NoSQL document database and application platform. (LGPL-2.1-only)

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Externalized Properties

Lightweight yet powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.

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Failsafe

Simple failure handling with retries and circuit breakers.

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Failsafe Actuator

Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.

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FastCSV

Performance-optimized, dependency-free and RFC 4180 compliant.

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fastexcel

High performance library to read and write large Excel (XLSX) worksheets.

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fastjson

Very fast processor with no additional dependencies and full data binding.

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fastutil

Fast and compact type-specific collections.

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Faux Pas

Library that simplifies error handling by circumventing the issue that none of the functional interfaces in the Java Runtime is allowed by default to throw checked exceptions.

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Feather

Ultra-lightweight, JSR-330-compliant dependency injection library.

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Feign

HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.

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FF4J

Feature Flags for Java.

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FileUpload

File upload capability for your servlets and web applications.

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Finder

Java library inspired by the UNIX find command.

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Firefly

Asynchronous framework for rapid development of high-performance web application.

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Fixture Factory

Generates fake objects from a template.

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FizzBuzz Enterprise Edition

No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)

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FlatBuffers

Memory-efficient serialization library that can access serialized data without unpacking and parsing it.

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Flatfile

Java library for working with flat data structures.

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FlexyPool

Brings metrics and failover strategies to the most common connection pooling solutions.

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Flogger

Flogger is a fluent logging API for Java. It supports a wide variety of features, and has many benefits over existing logging APIs.

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flowable

Compact and efficient workflow and business process management platform.

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Fluency

High throughput data ingestion logger to Fluentd and Fluent Bit.

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flyingsaucer

XML/XHTML and CSS 2.1 renderer. (LGPL-2.1-or-later)

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Flyway

Simple database migration tool.

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FreeBuilder

Automatically generates the Builder pattern.

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Freemarker

Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.

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FST

JDK-compatible, high-performance object graph serialization.

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fswatch

Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.

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Fugue

Functional extensions to Guava.

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Functional Java

Implements numerous basic and advanced programming abstractions that assist composition-oriented development.

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Functor

Function that can be manipulated as an object, or an object representing a single, generic function.

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Fury

Blazing fast object graph serialization framework powered by JIT and zero-copy.

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FXGL

JavaFX Game Development Framework.

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Gatling

Load testing tool designed for ease of use, maintainability and high performance.

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Geci

Discovers files that need generated code, updates automatically and writes to the source with a convenient API.

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Genson

Powerful and easy-to-use Java-to-JSON conversion library.

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Geo

GeoHash utilities in Java.

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GeoTools

Library that provides tools for geospatial data. (LGPL-2.1-only)

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Gephi

Cross-platform for visualizing and manipulating large graph networks. (GPL-3.0-only)

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Gestalt

Gestalt offers a comprehensive solution to the challenges of configuration management. It allows you to source configuration data from multiple inputs, merge them intelligently, and present them in a structured, type-safe manner.

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Getdown

System for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start.

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Glowroot

Open-source Java APM.

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Google Cloud Client Libraries

Client libraries for accessing Google Cloud services from Java applications.

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Google HTTP Client

Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.

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Governator

Extensions and utilities that enhance Google Guice.

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Graal

Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)

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Gradle

Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.

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Graph

General purpose graph APIs and algorithms.

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GraphHopper

Road-routing engine. Used as a Java library or standalone web service.

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GraphStream

Library for modeling and analyzing dynamic graphs.

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Graylog

Open-source aggregator suited for extended role and permission management. (GPL-3.0-only)

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GreenMail

In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL. (GPL-2.0-only)

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Grizzly

NIO framework. Used as a network layer in Glassfish.

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gRPC

RPC framework based on protobuf and HTTP/2.

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Gson

Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.

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Guava

Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.

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Guice

Lightweight and opinionated framework that completes Dagger.

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H2

Small SQL database notable for its in-memory functionality.

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H2GIS

Spatial extension of the H2 database. (LGPL-3.0-only)

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Hamcrest

Matchers that can be combined to create flexible expressions of intent.

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Handlebars.java

Logicless and semantic Mustache templates.

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hate

Builds hypermedia-friendly objects according to HAL specification.

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Hazelcast

Highly scalable in-memory datagrid with a free open-source version.

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Hdiv

Runtime application that repels application security risks included in the OWASP Top 10, including SQL injection, cross-site scripting, cross-site request forgery, data tampering, and brute force attacks.

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Helidon

Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile.

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Hermes

Fast and reliable message broker built on top of Kafka.

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HertzBeat

Real-time monitoring system with custom-monitor and agentless.

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Hibernate

Robust and widely used, with an active community. (LGPL-2.1-only)

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HikariCP

High-performance JDBC connection pool.

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H

HikariJSON

High-performance JSON parser, 2x faster than Jackson.

Projects
H

hippo4j

Dynamic and observable thread pool framework.

Projects
H

HK2

Lightweight and dynamic dependency injection framework.

Projects
H

honest-profiler

Low-overhead, bias-free sampling profiler.

Projects
H

HotswapAgent

Unlimited runtime class and resource redefinition. (GPL-2.0-only)

Projects
H

Hoverfly Java

Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.

Projects
H

HPPC

Primitive collections.

Projects
H

HSQLDB

HyperSQL 100% Java database.

Projects
H

HyperMinHash-java

Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.

Projects
I

I18n

Adds the feature of localized message bundles that consist of one or many localized texts that belong together.

Projects
I

iCal4j

Parse and build iCalendar RFC 5545 data models.

Projects
I

Id

Id is a component used to generate identifiers.

Projects
I

image-comparison

Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison.

Projects
I

ImageJ

Medical image processing application with an API.

Projects
I

Imaging

Image library.

Projects
I

Imgscalr

Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.

Projects
I

Immutables

Annotation processors to generate simple, safe and consistent value objects.

Projects
I

Indexer4j

Simple and light full text indexing and searching library.

Projects
I

Infer

Modern static analysis tool for verifying the correctness of code.

Projects
I

Infinispan

Highly concurrent key/value datastore used for caching.

Projects
I

ini4j

Provides an API for handling Windows' INI files.

Projects
I

inspectIT

Captures detailed run-time information via hooks that can be changed on the fly. It supports tracing over multiple systems via the OpenTracing API and can correlate the data with end user monitoring.

Projects
I

Instancio

Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension.

Projects
I

Intelligent java

Seamlessly integrate with remote deep learning and language models programmatically.

Projects
I

IO

Collection of I/O utilities.

Projects
I

IP2Location.io Java SDK

Wrapper for the IP2Location.io Geolocation API and the IP2WHOIS domain WHOIS API.

Projects
I

ISBN core

A small library that contains a representation object of ISBN-10 and ISBN-13 and tools to parse, validate and format one.

Projects
I

IzPack

Setup authoring tool for cross-platform deployments.

Projects
J

J2ObjC

Java-to-Objective-C translator for porting Android libraries to iOS.

Projects
J

J8Spec

Follows a Jasmine-like syntax.

Projects
J

jabba

Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.

Projects
J

Jackson

Similar to GSON, but offers performance gains if you need to instantiate the library more often.

Projects
J

jackson-dataformat-csv

Jackson extension for reading and writing CSV.

Projects
J

Jackson-datatype-money

Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.

Projects
J

jackson-modules-java8

Set of Jackson modules for Java 8 datatypes and features.

Projects
J

JaCoCo

Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.

Projects
J

JaCoP

Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)

Projects
J

JADE

Framework and environment for building and debugging multi-agent systems. (LGPL-2.0-only)

Projects
J

Jade4J

Implementation of Pug (formerly known as Jade).

Projects
J

Jaeger client

Jaeger client.

Projects
J

Jamal

Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling.

Projects
J

Jansi

ANSI escape codes to format console output.

Projects
J

JasperReports

Complex reporting engine. (LGPL-3.0-only)

Projects
J

Java Diff Utils

Utilities for text or data comparison and patching.

Projects
J

Java Faker

Port of Ruby's fake data generator.

Projects
J

Java Path Finder (JPF)

JVM formal verification tool containing a model checker and more. Created by NASA.

Projects
J

JavaCC

Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications.

Projects
J

JavaCPP

Provides efficient and easy access to native C++.

Projects
J

JavaCV

Java interface to OpenCV, FFmpeg, and much more.

Projects
J

Javaflow

Continuation implementation to capture the state of the application.

Projects
J

JavaFX

Successor of Swing.

Projects
J

Javalin

Microframework for web applications.

Projects
J

JavaMelody

Performance monitoring and profiling.

Projects
J

JavaPackager

Maven and Gradle plugin which provides an easy way to package Java applications in native Windows, macOS or GNU/Linux executables, and generate installers for them.

Projects
J

JavaParser

Parse, modify and generate Java code.

Projects
J

JavaPoet

API to generate source files.

Projects
J

Javassist

Tries to simplify bytecode editing.

Projects
J

JavaSymbolSolver

Symbol solver.

Projects
J

JavaVerbalExpressions

Library that helps with constructing difficult regular expressions.

Projects
J

JayWire

Lightweight dependency injection framework. (LGPL-3.0-only)

Projects
J

JBake

Static website generator.

Projects
J

JBehave

Extensively configurable framework that describes stories.

Projects
J

jbock

Reflectionless command line parser.

Projects
J

JBot

Framework for building chatbots. (GPL-3.0-only)

Projects
J

JBox2D

Port of the renowned C++ 2D physics engine.

Projects
J

JCI

Java Compiler Interface.

Projects
J

JCommander

Command-line argument-parsing framework with custom types and validation via implementing interfaces.

Projects
J

JCS

Java Caching System.

Projects
J

JCTools

Concurrency tools currently missing from the JDK.

Projects
J

JCuda

JCuda offers Java bindings for CUDA and CUDA-related libraries.

Projects
J

JDA

Wrapping of the Discord REST API and its WebSocket events.

Projects
J

JDBI

Convenient abstraction of JDBC.

Projects
J

jDeploy

Deploy desktop apps as native Mac, Windows or Linux bundles.

Projects
J

Jedis

Small client for interaction with Redis, with methods for commands.

Projects
J

Jelly

XML based scripting and processing engine.

Projects
J

jenv

Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS.

Projects
J

JeroMQ

Implementation of ZeroMQ.

Projects
J

Jersey

JAX-RS reference implementation.

Projects
J

Jest

Client for the Elasticsearch REST API.

Projects
J

jetcd

Client library for etcd.

Projects
J

Jetty

Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.

Projects
J

Jexer

Advanced console (and Swing) text user interface (TUI) library, with mouse-draggable windows, built-in terminal window manager, and sixel image support. Looks like Turbo Vision.

Projects
J

Jexl

Expression language which extends the Expression Language of the JSTL.

Projects
J

jFairy

Fake data generator.

Projects
J

JFlex

Lexical analyzer generator.

Projects
J

JFreeChart

2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)

Projects
J

Jgeohash

Library for using the GeoHash algorithm.

Projects
J

JGit

Lightweight, pure Java library implementing the Git version control system.

Projects
J

JGiven

Provides a fluent API which allows for simpler composition.

Projects
J

JGraphT

Graph library that provides mathematical graph-theory objects and algorithms.

Projects
J

JGraphX

Library for visualizing (mainly Swing) and interacting with node-edge graphs.

Projects
J

jGRASP

Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.

Projects
J

JGroups

Toolkit for reliable messaging and cluster creation.

Projects
J

jHiccup

Logs and records platform JVM stalls.

Projects
J

JHipster

Yeoman source code generator for Spring Boot and AngularJS.

Projects
J

Jimfs

In-memory file system.

Projects
J

Jinq

Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).

Projects
J

JITWatch

Analyze the JIT compiler optimisations made by the HotSpot JVM.

Projects
J

jjwt

JSON web token for Java and Android.

Projects
J

JKScope

Java scope functions inspired by Kotlin.

Projects
J

JLine

Includes features from modern shells like completion or history.

Projects
J

jlink.online

Builds optimized runtimes over HTTP.

Projects
J

JMapper

Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.

Projects
J

JMeter DSL.java

Load tests with JMeter as simple as a JUnit test.

Projects
J

JMH

Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM. (GPL-2.0 only WITH Classpath-exception-2.0)

Projects
J

JMLOK 2.0

Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)

Projects
J

JMockit

Integration testing, API mocking and faking, and code coverage.

Projects
J

jMolecules

Annotations and interfaces to express design and architecture concepts in code.

Projects
J

jMonkeyEngine

Game engine for modern 3D development.

Projects
J

jmxtrans

Connect to multiple JVMs and query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVM attributes. Supports different output writes, including Graphite, Ganglia, and StatsD.

Projects
J

JNA

Work with native libraries without writing JNI. Also provides interfaces to common system libraries.

Projects
J

JNet

JNet allows to use dynamically register url stream handlers through the java.net API.

Projects
J

JNR

Work with native libraries without writing JNI. Also provides interfaces to common system libraries. Same goals as JNA, but faster, and serves as the basis for the upcoming Project Panama.

Projects
J

JobRunr

Job scheduling library which utilizes lambdas for fire-and-forget, delayed and recurring jobs. Guarantees execution by single scheduler instance using optimistic locking. Has features for persistence, minimal dependencies and is embeddable.

Projects
J

Joda-Beans

Small framework that adds queryable properties to Java, enhancing JavaBeans.

Projects
J

Joda-Money

Basic currency and money classes and algorithms not provided by the JDK.

Projects
J

Jollyday

Determines the holidays for a given year, country/name and eventually state/region.

Projects
J

Jolokia

JMX over REST.

Projects
J

Jolt

JSON to JSON transformation tool.

Projects
J

Jooby

Scalable, fast and modular micro-framework that offers multiple programming models.

Projects
J

jOOQ

Generates typesafe code based on SQL schema.

Projects
J

jOOR

jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.

Projects
J

jOOX

Simple wrapper for the org.w3c.dom package, to allow for fluent XML document creation and manipulation with an API inspired by jQuery.

Projects
J

jOOλ

Extension to Java 8 that aims to fix gaps in lambda by providing numerous missing types and a rich set of sequential Stream API additions.

Projects
J

JPad

Snippet runner.

Projects
J

jQAssistant

Static code analysis with Neo4J-based query language. (GPL-3.0-only)

Projects
J

jqwik

Engine for property-based testing built on JUnit 5.

Projects
J

JSAT

Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)

Projects
J

JSON-io

Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.

Projects
J

JSON-LD

JSON-LD implementation.

Projects
J

JSONAssert

Simplifies testing JSON strings.

Projects
J

jsoniter

Fast and flexible library with iterator and lazy parsing API.

Projects
J

JsonPath

Extract data from JSON using XPATH-like syntax.

Projects
J

JsonSurfer

Streaming JsonPath processor dedicated to processing big and complicated JSON data.

Projects
J

JsonUnit

Library that simplifies JSON comparison in tests.

Projects
J

jsoup

Scrapes, parses, manipulates and cleans HTML.

Projects
J

jstachio

Typesafe Mustache templating engine.

Projects
J

jsweet

Source transpiler to TypeScript/JavaScript.

Projects
J

jte

Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.

Projects
J

Jtwig

Modular, configurable and fully tested template engine.

Projects
J

JUnit

Common testing framework.

Projects
J

junit-dataprovider

TestNG-like data provider/runner for JUnit.

Projects
J

Jwks RSA

JSON Web Key Set parser.

Projects
J

jwt-java

Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API.

Projects
J

JXPath

Utilities for manipulating Java Beans using the XPath syntax.

Projects
K

KAConf

Annotation-based configuration system for Java and Kotlin.

Projects
K

Kalium

Binding for the Networking and Cryptography (NaCl) library.

Projects
K

Karate

DSL that combines API test-automation, mocks and performance-testing making testing REST/HTTP services easy.

Projects
K

KeenType

Modernized version of a Java-based implementation of the New Typesetting System, which was heavily based on Donald E. Knuth's original TeX.

Projects
K

KeY

Formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. Uses JML for specification and symbolic execution for verification. (GPL-2.0-or-later)

Projects
K

Keycloak

Integrated SSO and IDM for browser apps and RESTful web services.

Projects
K

Keywhiz

System for distributing and managing secrets.

Projects
K

Kibana

Analyzes and visualizes log files. Some features require payment.

Projects
K

Koloboke

Carefully designed extension of the Java Collections Framework with primitive specializations and more.

Projects
K

Kryo

Fast and efficient object graph serialization framework.

Projects
K

KryoNet

Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.

Projects
K

kubernetes-client

Client provides access to the full Kubernetes & OpenShift REST APIs via a fluent DSL.

Projects
L

Lamdba Behave

Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.

Projects
L

Lang

Provides extra functionality for classes in java.lang.

Projects
L

LangChain4j

Simplifies integration of LLMs with unified APIs and a comprehensive toolbox.

Projects
L

Lanterna

Easy console text-GUI library, similar to curses. (LGPL-3.0-only)

Projects
L

LatencyUtils

Utilities for latency measurement and reporting.

Projects
L

Leaf

Distributed ID generate service.

Projects
L

Lettuce

Lettuce is a scalable Redis client for building non-blocking Reactive applications.

Projects
L

Liberica JDK

Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
L

libGDX

All-round cross-platform, high-level framework.

Projects
L

Light-4J

Fast, lightweight and productive microservices framework with built-in security.

Projects
L

LingPipe

Toolkit for tasks ranging from POS tagging to sentiment analysis.

Projects
L

Liquibase

Database-independent library for tracking, managing and applying database schema changes.

Projects
L

Litiengine

AWT-based, lightweight 2D game engine.

Projects
L

LittleProxy

High performance HTTP proxy atop Netty's event-based networking library.

Projects
L

log-capture

Captures log entries and provides assertions for unit and integration testing.

Projects
L

LoganSquare

JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library.

Projects
L

Logback

Robust logging library with interesting configuration options via Groovy.

Projects
L

Logbook

Extensible, open-source library for HTTP request and response logging.

Projects
L

LogCaptor

Captures log entries for unit testing purposes.

Projects
L

Logging

Wrapper around a variety of logging API implementations.

Projects
L

LogicNG

Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.

Projects
L

Logstash

Tool for managing log files.

Projects
L

Lombok

Code generator that aims to reduce verbosity.

Projects
L

LWJGL

Robust framework that abstracts libraries like OpenGL/CL/AL.

Projects
M

m2cgen

CLI tool to transpile models into native code.

Projects
M

Maker

Provides low level bytecode generation.

Projects
M

Manifold

Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.

Projects
M

MapDB

Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.

Projects
M

Mapsforge

Map rendering based on OpenStreetMap data. (LGPL-3.0-only)

Projects
M

MapStruct

Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.

Projects
M

MariaDB4j

Launcher for MariaDB that requires no installation or external dependencies.

Projects
M

Math

Lightweight, self-contained mathematics and statistics components.

Projects
M

Maven Wrapper

Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.

Projects
M

MCP Java SDK

Enables applications to interact with AI models and tools through a standardized interface (i.e. Model Context Protocol), supporting both synchronous and asynchronous communication patterns.

Projects
M

Membrane Service Proxy

Open-source, reverse-proxy framework.

Projects
M

MessagePack

Efficient binary serialization format.

Projects
M

methanol

HTTP client extensions library.

Projects
M

microconfig

Configuration system designed for microservices which helps to separate configuration from code. The configuration for different services can have common and specific parts and can be dynamically distributed.

Projects
M

Micrometer

Vendor-neutral metrics/observability facade for the most popular metrics/observability libraries.

Projects
M

Micrometer Tracing

Vendor-neutral distributed tracing facade for the most popular tracer libraries.

Projects
M

Micronaut

Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.

Projects
M

Microserver

Convenient, extensible microservices plugin system for Spring & Spring Boot. With more than 30 plugins and growing, it supports both micro-monolith and pure microservices styles.

Projects
M

Microsoft JDK

Microsoft Build of OpenJDK, Free, Open Source, Freshly Brewed!

Projects
M

MINA

Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.

Projects
M

Mines Java Toolkit

Library for geophysical scientific computation, visualization and digital signal analysis.

Projects
M

Mini2Dx

Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games.

Projects
M

MinimalFTP

Lightweight, small and customizable FTP server.

Projects
M

minio-java

Provides simple APIs to access any Amazon S3-compatible object storage server.

Projects
M

Mirror

Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.

Projects
M

Mixin

Manipulate bytecode at runtime using real Java code.

Projects
M

MobileUI

Cross-platform framework for developing mobile apps with native UI in Java and Kotlin.

Projects
M

Mockito

Mocking framework that lets you write tests with a clean and simple API.

Projects
M

Mockneat

Another fake data generator.

Projects
M

MockServer

Allows mocking of systems integrated with HTTPS.

Projects
M

Moco

Concise web services for stubs and mocks.

Projects
M

Modality

Lightweight ORM with database reverse engineering features.

Projects
M

ModelMapper

Intelligent object mapping library that automatically maps objects to each other.

Projects
M

Modern Java - A Guide to Java 8

Popular Java 8 guide.

Projects
M

Modernizer

Detect uses of legacy Java APIs.

Projects
M

Monitoring

Monitoring aims to provide a simple but extensible monitoring solution for Java applications.

Projects
M

Morpheus

Provides a versatile two-dimensional memory efficient tabular data structure called a DataFrame to enable efficient in-memory analytics for scientific computing on the JVM.

Projects
M

Moshi

Modern JSON library, less opinionated and uses built-in types like List and Map.

Projects
M

Multi-OS Engine

Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.

Projects
M

Mutability Detector

Reports whether instances of a given class are immutable.

Projects
M

MyBatis

Couples objects with stored procedures or SQL statements.

Projects
M

MyBatis-Plus

A powerful enhanced toolkit of MyBatis for simplifying development.

Projects
N

Nabla

Nabla provides automatic differentiation classes that can generate derivative of any function implemented in the Java language.

Projects
N

Nacos

Dynamic service discovery, configuration and service management platform for building cloud native applications.

Projects
N

Nakadi

Provides a RESTful API on top of Kafka.

Projects
N

nanohttpd

Tiny, easily embeddable HTTP server.

Projects
N

Narayana

Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)

Projects
N

native-lib-loader

Native library loader for extracting and loading native libraries from Java.

Projects
N

NATS client

NATS client.

Projects
N

Nbvcxz

Advanced password strength estimation.

Projects
N

Net

Collection of network utilities and protocol implementations.

Projects
N

NetBeans

Provides integration for several Java SE and EE features, from database access to HTML5.

Projects
N

Netty

Framework for building high-performance network applications.

Projects
N

Neureka

A lightweight, platform independent, OpenCL accelerated nd-array/tensor library.

Projects
N

Ninja

Full-stack web framework.

Projects
N

NoException

Allows checked exceptions in functional interfaces and converts exceptions to Optional return.

Projects
N

nudge4j

Remote developer console from the browser for Java 8 via bytecode injection.

Projects
N

NullAway

Eliminates NullPointerExceptions with low build-time overhead.

Projects
O

OACC

Provides permission-based authorization services.

Projects
O

ObjectiveSql

ActiveRecord ORM for rapid development and convention over configuration.

Projects
O

Objenesis

Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.

Projects
O

OctoLinker

Browser extension which allows to navigate through code on GitHub more efficiently.

Projects
O

OGNL

Object-graph navigation language.

Projects
O

oj! Algorithms

High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.

Projects
O

Open HTML to PDF

Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.

Projects
O

Open JDK

Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
O

OpenAI-Java

Java libraries for using OpenAI's GPT-3 API.

Projects
O

OpenAM

Access management solution that includes authentication, SSO, authorization, federation, entitlements and web services security.

Projects
O

opencsv

Simple CSV parser.

Projects
O

OpenDJ

LDAPv3 compliant directory service, developed for the Java platform, providing a high performance, highly available, and secure store for the identities.

Projects
O

OpenIG

High-performance reverse proxy server with specialized session management and credential replay functionality.

Projects
O

OpenJ9

High performance, enterprise-calibre, flexibly licensed, openly-governed cross-platform JVM extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.

Projects
O

OpenJML

Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)

Projects
O

OpenPDF

Open-source iText fork. (LGPL-3.0-only & MPL-2.0)

Projects
O

OpenPGP

Interface to signing and verifying data using OpenPGP.

Projects
O

OpenRefine

Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.

Projects
O

OpenTelemetry

Instrument, generate, collect, and export telemetry data to help you analyze your software’s performance and behavior.

Projects
O

OpenTracing Toolbox

Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations.

Projects
O

OptaPlanner

Business planning and resource scheduling optimization solver.

Projects
O

Orekit

A low level space flight dynamics library providing basic elements (orbits, dates, attitude, frames...) and various algorithms (conversions, propagations, pointing...) to handle them.

Projects
O

Orienteer

Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.

Projects
O

Orika

JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.

Projects
O

Orson-Charts

Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG. (GPL-3.0-only)

Projects
O

Oryx 2

Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.

Projects
O

OTP-Java

One-time password generator library according to RFC 4226 (HOTP) and RFC 6238 (TOTP).

Projects
O

owner

Reduces boilerplate of properties.

Projects
P

p3c

Provides Alibaba's coding guidelines for PMD, IDEA and Eclipse.

Projects
P

p6spy

Enables logging for all JDBC transactions without changes to the code.

Projects
P

pac4j

Security engine.

Projects
P

packr

Packs JARs, assets and the JVM for native distribution on Windows, Linux and macOS.

Projects
P

Packrat

Gatherers library for Java Stream API. Gatherers can enhance streams with custom intermediate operations.

Projects
P

Pact JVM

Consumer-driven contract testing.

Projects
P

Parity

Platform for trading venues.

Projects
P

ParparVM

VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
P

Passay

Enforce password policy by validating candidate passwords against a configurable rule set.

Projects
P

Password4j

User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions.

Projects
P

Pebble

Inspired by Twig and separates itself with its inheritance feature and its easy-to-read syntax. It ships with built-in autoescaping for security and it includes integrated support for internationalization.

Projects
P

Performance

Small framework for microbenchmark clients, with implementations for Commons DBCP and Pool.

Projects
P

Permazen

Language-natural persistence layer.

Projects
P

Perses

Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.

Projects
P

Persistent Collection

Persistent and immutable analogue of the Java Collections Framework.

Projects
P

Philadelphia

Low-latency financial information exchange.

Projects
P

PHP Serializer

Serializing objects in the PHP serialization format.

Projects
P

picocli

ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.

Projects
P

Pinpoint

Open-source APM tool.

Projects
P

Pipeline

Provides a set of pipeline utilities designed around work queues that run in parallel to sequentially process data objects.

Projects
P

PipelinR

Small utility library for using handlers and commands with pipelines.

Projects
P

Pippo

Small, highly modularized, Sinatra-like framework.

Projects
P

PIT

Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.

Projects
P

Play

Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.

Projects
P

PMD

Source code analysis for finding bad coding practices.

Projects
P

pojo-tester

Automatically performs tests on basic POJO methods. (LGPL-3.0-only)

Projects
P

Polyglot for Maven

Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.

Projects
P

Pool

Generic object pooling component.

Projects
P

PowerMock

Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.

Projects
P

PrimeFaces

JSF framework with both free and commercial/support versions and frontend components.

Projects
P

Prometheus

Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.

Projects
P

Protégé

Provides an ontology editor and a framework to build knowledge-based systems.

Projects
P

Protobuf

Google's data interchange format.

Projects
P

protonpack

Collection of stream utilities.

Projects
P

Proxy

Library for creating dynamic proxies.

Projects
Q

Quarkus

Kubernetes stack tailored for the HotSpot and Graal VM.

Projects
Q

Quartz

Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.

Projects
Q

Quasar

Lightweight threads and actors for the JVM.

Projects
Q

Querydsl

Typesafe unified queries.

Projects
Q

QueryStream

Build JPA Criteria queries using a Stream-like API.

Projects
Q

QuestDB

High-performance SQL database for time series. Supports InfluxDB line protocol, PostgreSQL wire protocol, and REST.

Projects
R

RabbitMQ Java client

RabbitMQ client.

Projects
R

raml-tester

Tests if a request/response matches a given RAML definition.

Projects
R

Randomized Testing

JUnit test runner and plugins for running JUnit tests with pseudo-randomness.

Projects
R

Rapidoid

Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.

Projects
R

Ratpack

Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.

Projects
R

RDF

Common implementation of RDF 1.1 that could be implemented by systems on the JVM.

Projects
R

Reactive Streams

Provides a standard for asynchronous stream processing with non-blocking backpressure.

Projects
R

Reactor

A framework for building non-blocking applications on the JVM, providing support for reactive programming.

Projects
R

really-executable-jars-maven-plugin

Maven plugin for making self-executing JARs.

Projects
R

Realm

Mobile database to run directly inside phones, tablets or wearables.

Projects
R

Recaf

JVM reverse engineering toolkit, essentially an IDE for Java bytecode.

Projects
R

Record-Builder

Companion builder class, withers and templates for Java records.

Projects
R

RedHat Open JDK

RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
R

Redisson

Allows for distributed and scalable data structures on top of a Redis server.

Projects
R

RefactorFirst

Identifies and prioritizes God Classes and Highly Coupled classes.

Projects
R

ReflectASM

ReflectASM is a very small Java library that provides high performance reflection by using code generation.

Projects
R

Reflections

Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project.

Projects
R

reMap

Lambda and method handle-based mapping which requires code and not annotations if objects have different names.

Projects
R

requery

Modern, lightweight but powerful object mapping and SQL generator. Easily map to or create databases, or perform queries and updates from any Java-using platform.

Projects
R

resilience4j

Functional fault tolerance library.

Projects
R

REST Assured

DSL for easy testing of REST/HTTP services.

Projects
R

rest.li

Framework for building robust, scalable RESTful architectures using typesafe bindings and asynchronous, non-blocking IO with an end-to-end developer workflow that promotes clean practices, uniform interface design and consistent data modeling.

Projects
R

RESTEasy

Fully certified and portable implementation of the JAX-RS specification.

Projects
R

RestExpress

Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.

Projects
R

Restlet Framework

Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.

Projects
R

Retrofit

Typesafe REST client.

Projects
R

Ribbon

Client-side IPC library that is battle-tested in the cloud.

Projects
R

Riptide

Client-side response routing for Spring's RestTemplate.

Projects
R

RNG

Commons Rng provides implementations of pseudo-random numbers generators.

Projects
R

RoaringBitmap

Fast and efficient compressed bitmap.

Projects
R

Rocker

Optimized, memory efficient and speedy template engine producing statically typed, plain objects.

Projects
R

RR4J

RR4J is a tool that records java bytecode execution and later allows developers to replay locally.

Projects
R

RxJava

Allows for composing asynchronous and event-based programs using observable sequences.

Projects
S

SAP Machine

SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
S

SBE

Simple Binary Encoding, one of the fastest message formats around.

Projects
S

ScaleCube Services

Embeddable Cluster-Membership library based on SWIM and gossip protocol.

Projects
S

Scene Builder

Visual layout tool for JavaFX applications.

Projects
S

scrimage

Immutable, functional, and performant JVM library for manipulation of images.

Projects
S

SCXML

Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.

Projects
S

SDKMan

Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows.

Projects
S

Seata

Delivers high performance and easy to use distributed transaction services under a microservices architecture.

Projects
S

SecurityBuilder

Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.

Projects
S

Selfie

Snapshot testing (inline and on disk).

Projects
S

Selma

Annotation processor-based bean mapper.

Projects
S

Semver4j

Lightweight library that helps you handling semantic versioning with different modes.

Projects
S

Sentinel

Flow control component enabling reliability, resilience and monitoring for microservices.

Projects
S

Serenity BDD

Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.

Projects
S

ServiceTalk

Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.

Projects
S

shedlock

Makes sure that your scheduled tasks are executed at most once at the same time. If a task is being executed on one node, it acquires a lock which prevents execution of the same task from another node or thread.

Projects
S

Siddhi

Cloud native streaming and complex event processing engine.

Projects
S

Simple Java Mail

Mailing with a clean and fluent API.

Projects
S

SimpleFlatMapper

Simple database and CSV mapper.

Projects
S

Siren4J

Library for the Siren specification.

Projects
S

SLF4J

Abstraction layer/simple logging facade.

Projects
S

Smack

Cross-platform XMPP client library.

Projects
S

Smile

Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.

Projects
S

Smooks

Framework for fragment-based message processing. (Apache-2.0 OR LGPL-3.0-or-later)

Projects
S

SnapCode

Modern IDE for Java running in the browser, focused on education.

Projects
S

SnapKit

Modern Java UI library for both desktop and web.

Projects
S

SneakyThrow

Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.

Projects
S

SonarJava

Static analyzer for SonarQube & SonarLint. (LGPL-3.0-only)

Projects
S

Spark

Sinatra inspired framework.

Projects
S

Spatial4j

General-purpose spatial/geospatial library.

Projects
S

Speedment

Database access library that utilizes Java 8's Stream API for querying.

Projects
S

Spoon

Library for analyzing and transforming Java source code.

Projects
S

Spotbugs

Static analysis of bytecode to find potential bugs. (LGPL-2.1-only)

Projects
S

Spring

Provides many packages for dependency injection, aspect-oriented programming, security, etc.

Projects
S

Spring AI

Application framework for AI engineering for Spring.

Projects
S

Spring Data JPA MongoDB Expressions

Allows you to use MongoDB query language to query your relational database.

Projects
S

Spring HATEOAS

Standalone and Spring support for building hypermedia-based APIs using HAL, HAL FORMS, Collection+JSON, ALPS and UBER.

Projects
S

springdoc-openapi

Automates the generation of API documentation using Spring Boot projects.

Projects
S

Square

Integration with the Square API.

Projects
S

sshj

Programmatically use SSH, SCP or SFTP.

Projects
S

SSLContext-Kickstart

High-level SSL context builder for configuring HTTP clients with SSL/TLS.

Projects
S

Stagemonitor

Open-source performance monitoring and transaction tracing for JVM apps.

Projects
S

StormCrawler

SDK for building low-latency and scalable web crawlers.

Projects
S

StreamEx

Enhances Java 8 Streams.

Projects
S

StringTemplate

Template engine for generating source code, web pages, emails, or any other formatted text output.

Projects
S

Stripe

Integration with the Stripe API.

Projects
S

Sundial

Lightweight framework to simply define jobs, define triggers and start the scheduler.

Projects
S

Super CSV

Powerful CSV parser with support for Dozer, Joda-Time and Java 8.

Projects
S

Svix

Library for the Svix API to send webhooks and verify signatures.

Projects
S

Swagger

Standard, language-agnostic interface to REST APIs.

Projects
S

SWT

Graphical widget toolkit.

Projects
S

Sysmon

Lightweight platform monitoring tool for Java VMs.

Projects
T

ta4j

Library for technical analysis.

Projects
T

Tablesaw

Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.

Projects
T

Tabula

Extracts tables from PDF files.

Projects
T

Tail

Enable infinite recursion using tail call optimization.

Projects
T

Takes

Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.

Projects
T

Tape

Lightning-fast, transactional, file-based FIFO.

Projects
T

Telosys

Simple and light code generator available as an Eclipse Plugin and also as a CLI.

Projects
T

Temporal

Microservice orchestration platform, forked from Cadence but gRPC based.

Projects
T

Tess4J

JNA wrapper for Tesseract OCR API.

Projects
T

Testcontainers

Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

Projects
T

Text-IO

Aids the creation of full console-based applications.

Projects
T

Themis

Multi-platform high-level cryptographic library provides easy-to-use encryption for protecting sensitive data: secure messaging with forward secrecy, secure data storage (AES256GCM); suits for building end-to-end encrypted applications.

Projects
T

ThreeTen-Extra

Additional date-time classes that complement those in JDK 8.

Projects
T

Thumbnailator

High-quality thumbnail generation library.

Projects
T

Thymeleaf

Aims to be a substitute for JSP and works for XML files.

Projects
T

Time4J

Advanced date and time library. (LGPL-2.1-only)

Projects
T

Timefold

Flexible solver with Spring/Quarkus support and quickstarts for the Vehicle Routing Problem, Maintenance Scheduling, Employee Shift Scheduling and much more.

Projects
T

Tink

Provides a simple and misuse-proof API for common cryptographic tasks.

Projects
T

tinylog

Lightweight logging framework with static logger class.

Projects
T

TLS Channel

Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS.

Projects
T

Togglz

Implementation of the Feature Toggles pattern.

Projects
T

Topaz

Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC.

Projects
T

Tribuo

Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.

Projects
T

Trino

Distributed SQL query engine for big data.

Projects
T

Truth

Google's fluent assertion and proposition framework.

Projects
T

TwelveMonkeys

Collection of plugins that extend the number of supported image file formats.

Projects
T

TypeTools

Tools for resolving generic types.

Projects
U

Underscore-java

Port of Underscore.js functions.

Projects
U

Undertow

Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)

Projects
U

unirest-java

Simplified, lightweight HTTP client library.

Projects
U

uniVocity-parsers

One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.

Projects
U

urnlib

Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)

Projects
V

Vaadin

Full-stack open-source Java framework that simplifies web app development. Build complex, interactive applications with Java alone, and enhance with TypeScript and React components, without needing deep JavaScript, CSS, or HTML expertise.

Projects
V

Validator

Framework to define validators and validation rules in an xml file.

Projects
V

Vavr

Functional component library that provides persistent data types and functional control structures.

Projects
V

vert.x

Polyglot event-driven application framework.

Projects
V

VFS

Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.

Projects
V

Vibur DBCP

JDBC connection pool library with advanced performance monitoring capabilities.

Projects
V

vips-ffm

Comprehensive bindings for libvips, using Java's "Foreign Function & Memory" API.

Projects
V

Visual Studio Code

Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.

Projects
V

Void2D

High-level 2D game engine with built-in physics based on Swing.

Projects
V

vulkan4j

Vulkan, OpenGL ES2 and GLFW Memory Allocator bindings.

Projects
W

Weaver

Provides an easy way to enhance (weave) compiled bytecode.

Projects
W

webcam-capture

Library for using built-in and external webcams directly in Java.

Projects
W

webmagic

Scalable crawler with downloading, url management, content extraction and persistent.

Projects
W

WebTau

Test across REST-API, Graph QL, Browser, Database, CLI and Business Logic with consistent set of matchers and concepts.

Projects
W

Weka

Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)

Projects
W

weld-testing

Set of test framework extensions (JUnit 4, JUnit 5, Spock) to enhance the testing of CDI components via Weld. Supports Weld 5.

Projects
W

Which JDK

Overview of common JVMs with pros and cons.

Projects
W

WildFly

Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)

Projects
W

Wire

Clean, lightweight protocol buffers.

Projects
W

WireMock

Stubs and mocks web services.

Projects
W

Wisp

Simple library with minimal footprint and straightforward API.

Projects
X

XChart

Light-weight library for plotting data. Many customizable chart types are available.

Projects
X

XMLBeam

Processes XML by using annotations or XPath within code.

Projects
X

XMLUnit

Simplifies testing for XML output.

Projects
X

Xodus

Highly concurrent transactional schema-less and ACID-compliant embedded database.

Projects
Y

Yasson

Binding layer between classes and JSON documents similar to JAXB.

Projects
Y

yGuard

Obfuscation via renaming and shrinking.

Projects
Z

zerocell

Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.

Projects
Z

zipkin

Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.

Projects
Z

zt-exec

Provides a unified API to Apache Commons Exec and ProcessBuilder.

Projects
Z

zt-process-killer

Stops processes started from Java or the system processes via PID.

Projects
Z

Zulu

OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)

Projects
Z

Zuul

Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.

Projects
Z

ZXing

Multi-format 1D/2D barcode image processing library.

Projects

Resources(83 items)

1

140 Second Ducklings

Short videos on Twitter explaining Java debugging in depth.

Resources
A

A Bootiful Podcast

Resources
A

Adam Bien

Freelance author, JavaOne Rockstar speaker, consultant, Java Champion.

Resources
A

Aleksey Shipilëv

Performance geek, benchmarking czar, concurrency bug hunter.

Resources
A

Antonio Goncalves

Java Champion, JUG Leader, Devoxx France, Java EE 6/7, JCP, Author.

Resources
A

Arun Gupta

Java Champion, JavaOne Rockstar, JUG Leader, Devoxx4Kids-er, VP of Developer Advocacy at Couchbase.

Resources
A

Awesome Annotation Processing

Resources
A

Awesome Graal

Resources
A

Awesome Gradle Plugins

Resources
A

Awesome Hybris

Resources
A

Awesome J2ME

Resources
A

Awesome Java libraries and hidden gems

Resources
A

Awesome JVM

Resources
A

Awesome Microservices

Resources
A

Awesome REST

Resources
A

Awesome Selenium

Resources
A

AwesomeJavaFX

Resources
B

Baeldung

Resources
B

Brian Goetz

Java Language Architect at Oracle.

Resources
B

Bruno Borges

Product Manager/Java Jock at Oracle.

Resources
C

Chris Engelbert

Open Source Enthusiast, Speaker, Developer, Developer Advocacy at TimescaleDB.

Resources
C

Chris Richardson

Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, \*POJOs in Action- author.

Resources
C

ciandcd

Resources
C

Core Java Volume I--Fundamentals

Resources
C

Core Java, Volume II--Advanced Features

Resources
D

Dzone

Resources
E

Ed Burns

Consulting Member of the Technical Staff at Oracle.

Resources
E

Effective Java (3rd Edition)

Resources
E

Eugen Paraschiv

Author of the Spring Security Course.

Resources
F

Foojay Podcast

Resources
F

foojay.io

Resources
G

Google Java Style

Resources
H

Head First Java (3rd Edition)

Resources
H

Heinz Kabutz

Java Champion, speaker, author of The Java Specialists' Newsletter, concurrency performance expert.

Resources
H

Holly Cummins

Technical Lead of IBM London's Bluemix Garage, Java Champion, developer, author, JavaOne rockstar.

Resources
I

InfoQ

Resources
I

Inside Java

(Official)

Resources
J

James Weaver

Java/JavaFX/IoT developer, author and speaker.

Resources
J

Java

Official Java Twitter account.

Resources
J

Java Algorithms and Clients

Resources
J

Java Concurrency Checklist

Resources
J

Java Concurrency in Practice

Resources
J

Java Developer Roadmap

Resources
J

Java Off Heap

Resources
J

Java Weekly

Resources
J

Java, SQL, and jOOQ

Resources
J

java.libhunt.com

Resources
J

Java.net

Resources
J

Javalobby

Resources
J

JavaWorld

Resources
J

Javin Paul

Well-known Java blogger.

Resources
J

JAXenter

Resources
J

Josh Long

Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.

Resources
L

Lukas Eder

Java Champion, speaker, Founder and CEO Data Geekery (jOOQ).

Resources
M

Mani Sarkar

Java champion, Polyglot, Software Crafter involved with @graalvm, AI/ML/DL, Data Science, Developer communities, speaker & blogger. Creator of couple of awesome lists like this one.

Resources
M

Mario Fusco

RedHatter, JUG coordinator, frequent speaker and author.

Resources
M

Mark Heckler

Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.

Resources
M

Markus Eisele

Java EE evangelist, Red Hat.

Resources
M

Martijn Verburg

London JUG co-leader, speaker, author, Java Champion and much more.

Resources
M

Martin Thompson

Pasty faced performance gangster.

Resources
M

Monica Beckwith

Performance consultant, JavaOne Rock Star.

Resources
O

OpenJDK

Official OpenJDK account.

Resources
O

OverOps Blog

Resources
P

Peter Lawrey

Peter Lawrey, Java performance expert.

Resources
R

r/java

Subreddit for the Java community.

Resources
R

Randy Shoup

Stitch Fix VP Engineering, speaker, JavaOne Rock Star.

Resources
R

RebelLabs

Resources
R

Reza Rahman

Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker.

Resources
S

Sander Mak

Java Champion, author.

Resources
S

Simon Maple

Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.

Resources
S

Spencer Gibb

Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal.

Resources
S

Stack Overflow

Question/answer platform.

Resources
S

Stephen Colebourne

Java Champion, speaker.

Resources
T

The Java Posse

Discontinued as of 02/2015.

Resources
T

The Well-Grounded Java Developer (2nd Edition)

Resources
T

TheServerSide.com

Resources
T

Thinking in Java

Resources
T

Trisha Gee

Java Champion and speaker.

Resources
U

Useful Java Links

Resources
V

Vanilla Java

Resources
V

Venkat Subramaniam

Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.

Resources
V

Vlad Mihalcea

Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book.

Resources
V

Voxxed

Resources