Like Dropbox, which is finally going public this week, San Francisco-based DocuSign has been an anticipated IPO for several years now. It’s raised over $500 million since it was founded in 2003 and has been valued at $3 billion. Kleiner Perkins, Bain Capital, Intel Capital, GV (Google Ventures) and Dell are amongst the many well-known names which have invested in DocuSign. But like many “unicorns” these days, the company took its time, spending 15 years as a private company.