Firebase , Firestore info
The top 10 things to know about Firestore when choosing a database for your app: https://medium.com/firebase-developers/the-top-10-things-to-know-about-firestore-when-choosing-a-database-for-your-app-a3b71b80d979
Cloud Firestore Data model: https://firebase.google.com/docs/firestore/data-model
Firebase Realtime Database: https://firebase.google.com/docs/database/web/structure-data