Java

Cardslibgabrielemariotti/cardslib

An Android library to build UI cards using the official Google CardView with extensive customization options.

Crawler4jyasserg/crawler4j

An open-source Java web crawler that provides a simple interface for multi-threaded web crawling.

ribbonNetflix/ribbon

A battle-tested client-side IPC library with built-in load balancing, fault tolerance, and support for HTTP/TCP/UDP protocols.

SQLBritesquare/sqlbrite

A lightweight wrapper around SQLiteOpenHelper that adds reactive stream semantics to SQL operations.

Azkaban (.5k)azkaban/azkaban

Azkaban is a batch workflow job scheduler created at LinkedIn to manage Hadoop jobs.

Drozermwrlabs/drozer

A security testing framework for Android that identifies vulnerabilities by interacting with apps, IPC endpoints, and the OS.

Mocodreamhead/moco

A lightweight Java framework for easily creating HTTP, REST, and WebSocket stub servers for integration testing.

Cyberduckiterate-ch/cyberduck

A libre file transfer client for macOS and Windows supporting FTP, SFTP, WebDAV, Amazon S3, Azure, OneDrive, and more.

GeoServergeoserver/geoserver

An open-source Java server for sharing and editing geospatial data using open standards.

JabRefJabRef/jabref

An open-source, cross-platform citation and reference management tool for BibTeX and BibLaTeX databases.

Furyalipay/fury

A high-performance multi-language serialization framework using JIT compilation and zero-copy techniques for fast data exchange.

failsafejhalterman/failsafe

A lightweight, zero-dependency Java library for implementing fault tolerance and resilience patterns.

Camunda (.2k)camunda/camunda-bpm-platform

An open-source BPMN platform for workflow and process automation, embeddable in Java applications.

OpenPDFLibrePDF/OpenPDF

An open-source Java library for creating, editing, rendering, and encrypting PDF documents, including HTML-to-PDF conversion.

MalmoMicrosoft/malmo

An AI experimentation platform built on Minecraft for training and researching intelligent agents in complex 3D environments.

Fernflowerfesh0r/fernflower

An analytical decompiler that converts Java bytecode back into readable Java source code, used in IntelliJ IDEA.

Javassistjboss-javassist/javassist

A Java bytecode engineering toolkit that simplifies runtime class definition and bytecode manipulation with source-level and bytecode-level APIs.

AWS SDK for Javaaws/aws-sdk-java

The official AWS SDK for Java 1.x enabling Java developers to work with Amazon Web Services (now in maintenance mode).

JMonkeyEnginejMonkeyEngine/jmonkeyengine

A 3-D game engine for adventurous Java developers, offering a complete open-source suite for cross-platform game development.

PowerMockpowermock/powermock

A Java testing framework that extends EasyMock and Mockito to mock static methods, final classes, private methods, and constructors.

shedlocklukas-krecan/ShedLock

A distributed lock for scheduled tasks ensuring at-most-once execution across multiple nodes.

spark-nlpJohnSnowLabs/spark-nlp

A state-of-the-art Natural Language Processing library built on Apache Spark, offering 100,000+ pretrained models and pipelines in 200+ languages.

java-trontronprotocol/java-tron

Java implementation of the TRON Protocol, a high-performance blockchain platform for decentralized applications.

XChangeknowm/XChange

A Java library providing a consistent API for trading and accessing market data across 60+ cryptocurrency exchanges.

NullAwayuber/NullAway

A fast, annotation-based null checker for Java that eliminates NullPointerExceptions with low build-time overhead.

NullAwayuber/NullAway

A fast annotation-based null checker for Java that eliminates NullPointerExceptions with low build-time overhead.

Status.imstatus-im/status-react

A free open-source mobile operating system for Ethereum, combining a messenger, browser, and gateway to decentralized applications.

Awaitilityawaitility/awaitility

A Java DSL for testing asynchronous systems by expressing expectations in a concise and readable manner.

IDDD SamplesVaughnVernon/IDDD_Samples

Reference implementations of Bounded Contexts from Vaughn Vernon's 'Implementing Domain-Driven Design' book.

JRubyjruby/jruby

A complete, high-performance implementation of the Ruby programming language that runs on the Java Virtual Machine (JVM).

RoaringBitmapRoaringBitmap/RoaringBitmap

A compressed bitmap data structure for Java that outperforms alternatives like WAH, EWAH, and Concise in speed and compression.

TerasologyMovingBlocks/Terasology

An open-source voxel world game engine and platform for creating diverse gameplay experiences in a block-based environment.

JCToolsJCTools/JCTools

High-performance concurrent data structures for the JVM, supplementing the Java standard library.

Apache Cordovaapache/cordova-android

Android platform library for building Cordova hybrid mobile apps with web technologies.

Tablesawjtablesaw/tablesaw

A Java dataframe and visualization library for data loading, cleaning, transformation, and analysis.

springdoc-openapispringdoc/springdoc-openapi

Automatically generates OpenAPI 3 documentation for Spring Boot applications, including Swagger UI integration.