Monitoring PubMed retractions: a Heroku-hosted Sinatra application

In a previous post analysing retractions from PubMed, I wrote:

It strikes me that it would be relatively easy to build a web application (Rails, Heroku), which constantly monitors retraction data at PubMed and generates a variety of statistics and charts.

“Relatively easy” it was. Let me introduce you to PMRetract, my first publicly-available web application.