What factors contributed to Clearbit's initial product-market fit, and what differentiates the company from incumbents in the market?

To be completely frank with you, what made us different was that we had an API that 1) you could sign up for with a credit card, and 2) was significantly easier to use than any of the other products out there. 

REST APIs were a newish thing then, and we built five nice ones: a person API, a company API, a watchlist API, a risk API, and a logo API. 

The initial idea for the company was data APIs for developers: so we’d get every different kind of company data, we'll build a really nice API on top of it, and sell that to developers.