OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and customers.
NotificationX - Best social proof and FOMO marketing solution for WordPress to increase conversion rates.
Subbscribe - Opt-in form to help you grow your web subscriptions
Nudgify - Nudgify is a Social Proof App that includes FOMO, Urgency and Review Nudges. Adding Social Proof notifications to your site helps you build trust and increase conversions on Shopify, Wordpress or any other platform.
Monarch - Social media sharing plugin for WordPress
Fomo - Fomo turns your site into the online equivalent of a busy store