Basecamp gave away its own framework for free, and GitHub was built on it.
In 2003 a Chicago design firm hired a Danish student, David Heinemeier Hansson, to build a tool for its own chaotic client work. He chose Ruby, then an obscure language. In July 2004, five months after the tool went on sale, he released the framework underneath it for free. He called it Ruby on Rails.
Basecamp on Brandseum