In fact, without specifying anything else, a Rails app deployed to Heroku will default to using webrick. Consequently, at Waza 2013 they revealed that webrick i

In fact, without specifying anything else, a Rails app deployed to Heroku will default to using webrick. Consequently, at Waza 2013 they revealed that webrick is the most used server at Heroku, and is 3x more popular than Thin. [0] [0] http://www.slideshare.net/heroku/heroku-secrets-waza-2013 http://www.slideshare.net/heroku/heroku-secrets-waza-2013