Agrid is an API of prices of services that received more than 500 quotes every day from more than 95k brides to more than 2k vendors on our platform. Started with a Ruby on Rails app that used PostgreSQL as database and Redis as in memory data structure store and then we decided to move to a Rails API combined with an AngularJS frontend app. Our stack was Ruby on Rails, PostgreSQL, Redis, AngularJS, APIs: Facebook, Google+, Foursquare, Google Places, Heroku