This SDK allows you to store files on your user's Google Drive account.
This is an OAuth API and you first must set up an account, projects and permissions in the Google Developer ConsoleDeveloper Console
Once you've created a project, go to 'APIs and Auth' and enable the 'Drive API' and 'Drive SDK'
Next, click 'Credentials' and create a new OAuth Client ID
Follow the prompt to configure the consent screen
Application Type: Web Application
Authorized Domains: http://localhost (for development)
Create Client ID
Follow the quickstart guide (starting at Step 2):Quickstart
Discussion of Realtime API Concepts and Applications
Firebase is a backend as a service (BaaS) that offers similar functionality to the Drive Realtime API.
They were recently bought by Google as well.Tutorial