Meteor or MeteorJS is one of the popular free and open source JavaScript web framework. It is  for building web and cross-platform mobile applications for Android and iOS platforms. Database is implemented with MongoDB. it also helps to publish-subscribe pattern along with the usage of the Distributed Data Protocol. Meteor helps to avoid writing the synchronized codes as it allows automatic propagation of the data changes to clients. So Meteor.js is a framework with which we can save time and effort.