Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
Snowball Smart Notifications - Get the notifications you want and none of the rest
CloudBoost.io - One Complete Database Service that does data-storage, search,real-time and a whole lot more.
Pingy - Check your site status from your menubar
Supabase - An open source Firebase alternative
Hooks Chats - Push notifications meet real time conversations