As usual in decentralized authentication posts, I'd like to mention Mozilla Persona[1] which is a decentralized third party authentication service over the open source BrowserID protocol.
I don't mean to diminish the author's work in any way; but if you're interested in these things and don't know about Persona, please look into it!
The right intrepation is that Mozilla is not funding the project, but the protocl (browser id) and Persona source code are still out there.
The downside is Mozilla MIGHT sunset their Persona infrastructure one day. But that's not a real concern because Mozilla is never interested in being people's Persona verifier. They were hoping Persona would take off and people would host their own bridge, instead of relying on Mozillia's.
I don't mean to diminish the author's work in any way; but if you're interested in these things and don't know about Persona, please look into it!
[1]: https://www.mozilla.org/en-US/persona/