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.
Apple App Analytics - Apple's very own iTunes Connect App Analytics
NotificationX - Best social proof and FOMO marketing solution for WordPress to increase conversion rates.
My Motiff - Allowing you to stay connected in realtime
Fomo - Fomo turns your site into the online equivalent of a busy store
Usage Analytics in appFigures - Track usage for your app along side downloads, ranks & more