What are some alternatives?
When comparing Zizozz and Clearbit Connect, you can also consider the following products
Hunter - Find all the email addresses related to a domain
RocketReach - RocketReach allows you to lookup email and phone for 250+ million professionals.
Clearbit - Clearbit provides Business Intelligence APIs
FindThatLead Prospector - Feed your sales team with daily leads.
Slik Prospector - Find anyone's email. No bounces.
Email Generator - Get +50 email combinations and validate them with Rapportive