Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
Clearbit - Clearbit provides Business Intelligence APIs
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
MailClark - The Slack bot for external communications
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.