HubSpot Marketing Hub - HubSpot is a cloud-based inbound marketing software that allows businesses to transform the way that they market online.
AnyMailFinder.com - Find anyone's email address
Marketo - Marketo's powerful marketing automation software helps marketers master the art & science of digital marketing to engage customers and prospects.
GitHub Email Finder - Find the email of any GitHub Developer using their GitHub username.
ActiveCampaign - Integrated email marketing, marketing automation, and small business CRM. Send beautiful newsletters, setup behavioral based automations, and benefit from sales automation.
Hunter - Find all the email addresses related to a domain