Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Lusha - Search less. Sell more.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.
Nextcloud Contacts - The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server.
Clearbit - Clearbit provides Business Intelligence APIs