Firebase :- The Realtime App Platform. Firebase is a cloud service designed to power real-time, collaborative applications. Simply add the Firebase library to your application to gain access to a shared data structure; any changes you make to that data are automatically synchronized with the Firebase cloud and with other clients within milliseconds.
Back4App :- An easy-to-use, flexible and scalable backend based on Parse Platform. It allows developers to create apps faster building the backend with no code, host with no infrastructure hassles and scale with no technical locks.