Server side OAuth2 in Dart
The description says client library but also that it only works with 'dart:io' which means it is for the serverhttp://pub.dartlang.org/packages/oauth2
and
http://pub.dartlang.org/packages/google_oauth2_v2_api (client and server)
There is also a complete OAuth2 implementation for the Angel framework:https://github.com/angel-dart/oauth2
The included code abstracts over the OAuth2 transport itself; the storage, database, etc. is up to your choice.
Aqueduct (http://aqueduct.io/docs/tut/oauth2/) has a complete oauth2 implementation in dart.
Unfortunately it relies on PostgreSQL as a repository for oauth2 tokens. That means at least one db access per request to retrieve token.
But the sources are there and you can try something better....