I am just wondering that, is it safe to use your primary google account details to sign in into 3rd party apps like reeder?
If it is safe then how exactly that authentication works. I am sure they are not using OpenID because I checked the applications that I gave access to and this app was not listed there.
Best Answer
Authentication and Authorization for Google APIs has the basics of their mechanism.
It seems, you now need to do a two-factor authentication on reeder.
Here is a recent metafilter thread on trusting 3rd-party apps with login info.