UProc for Sheets - Boost your sales, marketing and IT tasks from Google Sheets
Hunter - Find all the email addresses related to a domain
Sheetlist - Discover free Google Sheets for marketing, finance and more
Snov.io - More leads. More sales. More revenue.
Mattermark in Salesforce AppExchange - Automatically enrich leads in Salesforce with Mattermark
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.