Getting people and profile information - Google+ Platform. Oauth 2.0 - second step in creating google plus login button. Platform. To take advantage of all of the benefits of Google+ Sign-In you must use a hybrid server-side flow where a user authorizes your app on the client side using the JavaScript API client and you send a special one-time authorization code to your server.
Your server exchanges this one-time-use code to acquire its own access and refresh tokens from Google for the server to be able to make its own API calls, which can be done while the user is offline. Quickstart samples - Google+ Platform. Google Plus Over the Air installs via server-side oauth. Android app installs from your web site - Google+ Platform.