I have a doubt about Google Login and Developer API for Google Login.
Some authentication Apps like Gigya and BC oAuth need an API key with a Google application. But currently, Social Connect does n’t need it. What is the difference between two methods and any advantages using a registered application?
The only answer I can think of is maybe these apps (Gigya, BC) use an older protocol called AuthSub, or these apps are asking for greater security. Here are the benefits to registering your app with Google:
are recognized by Google. The Google “Access Consent” page, which asks users to grant/deny access to their account when requested by third-party applications, omits default text cautioning that the site is not trusted.
can provide a better level of security for their users.
get access to certain services (such as some Google Data API feeds) that require third-party applications to be registered.
enables “2-legged” OAuth access for Google Apps domain administrators.