Firebase - Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.
Supabase - An open source Firebase alternative
Etebase - Etebase makes it easy to build end-to-end encrypted applications by taking care of the encryption and its related challenges.
RethinkDB - The open-source database for the realtime web
Meteor - Meteor is a set of new technologies for building top-quality web apps in a fraction of the time.
GUN - Self-hosted Firebase.