We built a search engine that shows you the most engaging stories/topics being shared across Twitter, Facebook, Linkedin, and Google+. We crawled over 15 million articles the past 3 months, retrieved the total number of Facebook likes, tweets, Google+’s etc and built a search index around it.

Here's what our infrastructure looks like:

Rails/Redis: We use the Sidekiq gem as a message queue. We have hundreds of workers that do the crawling, data mining, and number crunching.

ElasticSearch: We built the search index using ElasticSearch, with the data imported from our Postgres database.

AngularJS: Front-end is built using AngularJS and Laravel 4 (PHP), which sends the requests to our Rails server in the backend.