Desktop/Android/HTML5/iOS Java game development framework

Tools to work with android .dex and java .class files

A barebones WebSocket client and server implementation written in 100% Java.

Java JsonPath implementation

Java interface to OpenCV, FFmpeg, and more

GraphQL Java implementation

Java implementation of JSON Web Token (JWT)

Advanced Java Redis client for thread-safe sync, async, and reactive usage. Supports Cluster, Sentinel, Pipelining, and codecs.

Java library to create bots using Telegram Bots API

A library for working with Bitcoin

Decompiler from Java bytecode to Java, used in IntelliJ IDEA.

Actor Messaging platform

A modular and portable open source XMPP client library written in Java for Android and Java (SE) VMs

Telegram Bot API for Java

Java client library for Google Maps API Web Services

MessagePack serializer implementation for Java / msgpack.org[Java]

Java Template Engine

Botan.io libs & SDK

Skype API written in Java. Does not support P2P chats

Telegram Api library for java

Tiny HTTP router library for Netty, that can route and create reverse routes

Java MTProto implementation

Ghost Driver is an implementation of the Remote WebDriver Wire protocol, using PhantomJS as back-end

hqx-java is a Java port of hqx, a fast, high-quality magnification filter designed for pixel art.

Java TypeLanguage core library

Microemulator

Decentralized ImageBoard

Java library for DaData.Ru REST API