IndieAuth is an identity layer on top of OAuth 2.0 [RFC6749], primarily used to obtain
an OAuth 2.0 Bearer Token [RFC6750] for use by [Micropub] clients. End-Users
and Clients are all represented by URLs. IndieAuth enables Clients to
verify the identity of an End-User, as well as to obtain an access
token that can be used to access resources under the control of the
End-User.