Heroku is probably the closest case study, in that they started as (and mostly remained in the popular conscience) a Ruby on Rails host. I believe they sold for

Heroku is probably the closest case study, in that they started as (and mostly remained in the popular conscience) a Ruby on Rails host. I believe they sold for $200+ million. Not a "unicorn", but not a small exit, for such a short period of time. They were only around as an independent company for a few years.