Google Sign-In is a secure authentication system that reduces the burden of login for your users, by enabling them to sign in with their Google Account—the same account they already use with Gmail, Play, Google+, and other Google services. Google Sign-In is also your gateway to connecting with Google’s users and services in a secure manner. You can give your users the opportunity to pay with Google Pay, share with their Google-wide contacts, save a file to Drive, add an event to Calendar, and more. Integrate Google’s user-centric APIs and services inside your app to help your users take action and convert.

A circular ImageView for Android applications.

A software library to view analytics, measure ad performance and build audiences for ad targeting within the Facebook framework.

Build Realtime Apps. A powerful API to store and sync data in realtime.

An image loading and caching library for Android focused on smooth scrolling

In-app Billing is a Google Play service that lets you sell digital content from inside your applications. You can use the service to sell a wide range of content, including downloadable content such as media files or photos, virtual content such as game levels or potions, premium services and features, and more.

Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. Google uses Protocol Buffers for almost all of its internal RPC protocols and file formats.

The missing bridge between Java and native C++. JavaCPP provides efficient access to native C++ inside Java, not unlike the way some C/C++ compilers interact with assembly language. No need to invent new languages such as C++/CLI or Cython. Under the hood, it uses JNI, so it works with all Java implementations, including Android. In contrast to other approaches (SWIG, CableSwig, JNIGeneratorApp, cxxwrap, JNIWrapper, Platform Invoke, GlueGen, JNIDirect, JNA, JNIEasy, JniMarshall, JNative, J/Invoke, HawtJNI, BridJ, etc.), it supports naturally and efficiently many features of the C++ language often considered problematic, including overloaded operators, template classes and functions, member function pointers, callback functions, functors, nested struct definitions, variable length arguments, nested namespaces, large data structures containing arbitrary cycles, multiple inheritance, passing/returning by value/reference/vector, anonymous unions, bit fields, exceptions, destructors and garbage collection. Obviously, neatly supporting the whole of C++ would require more work (although one could argue about the intrinsic neatness of C++), but I am releasing it here as a proof of concept. I have already used it to produce complete interfaces to OpenCV, FFmpeg, libdc1394, PGR FlyCapture, OpenKinect, videoInput, and ARToolKitPlus as part of JavaCV. The new JavaCPP Presets subproject also demonstrates early parsing capabilities of C/C++ header files that already show promising and useful results with at least FFmpeg, libdc1394, OpenKinect, videoInput, and ARToolKitPlus.

Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users. It is embedded in J2SE 6 as the default Java scripting engine.

Reactive Extensions for Async Programming specifically tailored for Android.