OAuth 2 in Microsoft.Owin.Security.OAuth - nordvall/TokenClient GitHub Wiki

Microsoft.Owin.Security.OAuth is a NuGet package containing a base implementation of the OAuth 2 protocol. When added to an Owin application, it finds incoming OAuth protocol requests, but you as a developer needs to validate the incoming credentials and issue the outgoing claims.

An example implementation of this component can be found in the "Single Page Application" project template in Visual Studio 2013.

Another example can be found here: Embedding a simple Username/Password Authorization Server in Web API v2 - leastprivilege.com