BuiltWith - Find out the technology behind websites

GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!

Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.

Elevatr Email Marketing Automation - Fast and easy email marketing software

WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.

Google Sheets Email Marketing - Email automation and validations directly from Google Sheets