The HackHall app is a true MVC application. It has the REST API server with a front-end client that is written in Backbone.js and Underscore. For the purpose of this chapter, we’ll illustrate how to use Express.js with MongoDB via Mongoose ORM/ODM (object-relational mapping/object-document mapping) for the back-end REST API server. In addition, the project utilizes OAuth directly and via Passport, sessions, and Mocha for TDD. It’s hosted on Heroku and is in active development (see the nearby Note).