RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

Netty project - an event-driven asynchronous network application framework

Telegram for Android source

Stetho is a debug bridge for Android applications, enabling the powerful Chrome Developer Tools and much more.

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

DEPRECATED

Asynchronous socket, http(s) (client+server) and websocket library for android. Based on nio, not threads.

A fast dependency injector for Android and Java.

Android Asynchronous Networking and Image Loading

A sample Android app which showcases advanced usage of Dagger among other open source libraries.

[Archived] Highlight the best bits of your app to users quickly, simply, and cool...ly

Simple OAuth library for Java

An extensible multilanguage static code analyzer.

The official AWS SDK for Java 1.x (In Maintenance Mode, End-of-Life on 12/31/2025). The AWS SDK for Java 2.x is available here: https://github.com/aws/aws-sdk-java-v2/

Allows Android apps to interact with BLE beacons

Twitter4J is an open-source Java library for the Twitter API.

Name UI states, navigate between them, remember where you've been.

Command-line tool to count per-package methods in Android .dex files

Sample to show how to implement blur graphical tricks

For more info see

WebSocket & WAMP in Java for Android and Java 8

Kick-starts Android application development.

A command line tool which parses and converts android bugreport files into more human readable html reports.

Android-BitmapCache is a specialised cache, for use with Android Bitmap objects.

Spring for Android Sample Applications

Bare minimum websockets (hybi13/RFC) client for Android