Firebase is a real-time NoSQL cloud database (but also cloud storage and messaging service and authentication service and — see here) that helps you build apps without building the backend (or letting you to add someone later — see functions).

What is Firebase and why it is used?

Google Firebase is a Google-backed application development software that enables developers to develop iOS, Android and Web apps. Firebase provides tools for tracking analytics, reporting and fixing app crashes, creating marketing and product experiment.

Is angular Firebase free?

The package @angular/fire has a built-in deploy functionality. You can read the documentation here. Deploy angular/any site on Firebase absolutely free using below steps: Prerequisite: Sign in into Firebase console using google account and then create project for angular app.