Clearbit provides business intelligence APIs to help research and qualify leads, amongst other use cases. The REST APIs take an email address, or a domain name, and return a whole host of person and company information, from names, titles, and social handles to company headcount, market verticals, funding and more. Prominent clients include Stripe, Zendesk, Asana and Intercom. Angel investors include Naval Ravikant, Othman Laraki, Hiten Shah, Ariel Poler, and Ilya Sukhar. The product is available on a subscription basis.