J2ObjC is an open-source command-line tool from Google that translates Java code to Objective-C for the iOS (iPhone/iPad) platform. This tool enables Java code to be part of an iOS application's build, as no editing of the generated files is necessary. The goal is to write an app's non-UI code (such as data access, or application logic) in Java, which is then shared by web apps (using GWT), Android apps, and iOS apps.

React Native enables you to build world-class application experiences on native platforms using a consistent developer experience based on JavaScript and React. The focus of React Native is on developer efficiency across all the platforms you care about - learn once, write anywhere. Facebook uses React Native in multiple production apps and will continue investing in React Native.

Xamarin’s Mono-based products enable .NET developers to use their existing code, libraries and tools (including Visual Studio*), as well as skills in .NET and the C# programming language, to create mobile applications for the industry’s most widely-used mobile devices, including Android-based smartphones and tablets, iPhone, iPad and iPod Touch.