Grabby - Grabby is a web-based service that allows you to extract email addresses from just about any website you wish.
Hunter - Find all the email addresses related to a domain
Norbert - Norbert is an online tool that helps you to find anyone’s corporate email address.
Snov.io - More leads. More sales. More revenue.
Wiza - Create email lists from Linkedin Sales Navigator
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.