I feel it is made for fast Oauth integration.
We use 4 oauth providers into one of our app, and it took us really 4 full days to implement them without bug. We are not Oauth experts but it was really boring and IMO useless implementation time.
Also I'm personaly making a client-side app on a Github page and it seems that with oauth.io I could make a serverless Facebook/Twitter authenticated app.
Also I'm personaly making a client-side app on a Github page and it seems that with oauth.io I could make a serverless Facebook/Twitter authenticated app.