WP Rocket - WP Rocket offers a caching plugin for Wordpress.
ConvertFlow - Convert the right people with the right calls-to-action at the right time using a personalized way to guide visitors to become customers.
Yoast - Yoast offers plugins to improve SEO and optimize web sites and blogs.
OptiMonk - OptiMonk is the most powerful Onsite Retargeting platform, that helps you increase the conversion rate of your site, and get more leads by recovering lost visitors.
Wordfence - Comprehensive security plugin for WordPress.
Crazy Egg - Through Crazy Egg's heat map and scroll map reports you can get an understanding of how your visitors engage with your website so you can boost your conversion rates.