Interesting story started from 2003...
Change is good, evolution, Transcendent Software, Agile, Ruby on Rails
"What’s number one on Joel Spolsky’s list of ‘Things You Should Never Do’?
“Rewrite your software from scratch.“
David Heinemeier Hansson disagrees.
In this talk, ‘Rewrite!‘ at Business of Software Conference USA 2015, David Heinemeier Hansson, Co-Founder, Basecamp, and Creator of Ruby on Rails explains why he disagrees and discusses his experience in rewriting the code for Basecamp, not once, but twice,"
Speaker slide decks from Business of Software Conference USA 2015 - Business of Software USA
But that was not the first major SaaS... much bigger story:
Salesforce.com - Wikipedia, the free encyclopedia