Something to be aware of is that as of the last time I checked (a month or two ago) most of these providers do not implement the finalized 2.0 specification [0]

Something to be aware of is that as of the last time I checked (a month or two ago) most of these providers do not implement the finalized 2.0 specification [0]. I was lucky enough to have to write an implementation recently, and using Google's and Facebook's docs as a reference often led to confusion. [0] http://tools.ietf.org/html/rfc6749 http://tools.ietf.org/html/rfc6749