Any startup looking to develop a mobile app for either iOS or Android, a web app or any application that requires a backend, should seriously consider using Firebase as a backend. Why? There are so many reasons for it, but I will try to explain as succinctly as possible.
Initial Zero Cost
Firebase comes at an initial zero cost with the spark plan. This allows you to do a lot. Once you hit the limitations of the free plan, then you have the option of the Flame plan at a fixed cost of $25/month or the pay as you go plan. This type of pricing is great because it allows you to keep costs to a minimum during your development phase.
Includes a NoSQL Database
Built-in federated authentication support