Popify App - Boost your conversions using social proof popups
HoverSignal - Increase your website's conversions with notifications
WP Social Proof - Social proof for WordPress Websites
AnyMailFinder.com - Find anyone's email address
SocialProofed - SocialProofed is the easy way to embed Instagram feeds, Facebook reviews, and Google testimonials on your website...in just 60 seconds!
Hunter - Find all the email addresses related to a domain