What is the difference between a Project and an App?

[Atlas Group]

Under the new upgrades, what is the difference between a Project and an App?

It appears on the surface that one project can have many apps associated with it. Does each app have to belong to one and only one Project? Or can an app belong to multiple projects? And how many projects are we allowed to have?

[Ian Barber]

Practically, a project is a unit for the Firebase services: a project can have a billing plan, and one set of owners/editors and so on. 

An app is a specific application on a single platform - for example an iOS client or a web client. A project can contain several apps, but an app can only be in one project. 

The slightly confusing thing is that sometimes one codebase is several apps - for example you might have two different variants of an Android app, one free and one paid - each can be a different Firebase app. Or you might have a development App that is separate from the release App. 

Usually, but not always, all apps for a given codebase will be in the same project. This lets them easily share the same backend services, the same quotas and so on. So you would have have your iOS, Android and web apps all in the same project. 

With regards to free and paid app splits, or dev and test, its largely up to you: people have successfully used both the same and separate projects depending on their specific needs. 

In terms of the limits: there is no limit on paid projects. There is a limit on the number of free apps, but it varies with different users, so there's not a hard and fast number.