AeroLeads - AeroLeads is a lead generation software which finds prospects with email and phone number.
DiscoverOrg - DiscoverOrg is an IT sales intelligence platform providing technology marketers access to data, IT org charts, and real time projects.
Hunter - Find all the email addresses related to a domain
Clearbit - Clearbit provides Business Intelligence APIs
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.