Meteor.js is a free and open-source, ultra-simple, full-stack JavaScript platform for developing modern, client reactive web and mobile Applications. It is written using Node.js and allows you to develop in one language JavaScript, with Meteor.js you send data over the wire, meaning the server sends data, not the HTML. Meteor.js is compatible with OS X, Windows, and Linux. It allows for quick prototyping and produces cross-platform (Android, iOS, Web) code.