TL;DR If you have very simple scenarios, like a single client application, a single API then it might not pay off to go OAuth 2.0, on the other hand, lots of different clients (browser-based, native mobile, server-side, etc) then sticking to OAuth 2.0 rules might make it more manageable than trying to roll your own … Read more
The redirect URI (where the response is returned to) has to be registered in the APIs console, and the error is indicating that you haven’t done that, or haven’t done it correctly. Go to the console for your project and look under API Access. You should see your client ID & client secret there, along … Read more
OpenID is about authentication (ie. proving who you are), OAuth is about authorisation (ie. to grant access to functionality/data/etc.. without having to deal with the original authentication). OAuth could be used in external partner sites to allow access to protected data without them having to re-authenticate a user. The blog post “OpenID versus OAuth from … Read more