Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
OneSignal - Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.
CloudBoost.io - One Complete Database Service that does data-storage, search,real-time and a whole lot more.
Truepush - Unleash limitless possibilities with Truepush and save up to $600 monthly. Free up to 10K Subscribers on all features.
Supabase - An open source Firebase alternative
Notix.co - NOTIX is an audience re-engagement service based on web and in-app push notifications that work for both desktop and mobile devices.