According to Wikipedia, Microsoft Active Directory Federation Services (ADFS) is: … a software component developed by Microsoft that can be installed on Windows Server operating systems to provide users with single sign-on access to systems and applications located across organizational boundaries. It uses a claims-based access control authorization model to maintain application security and implement federated identity. ADFS can provide Single sign as an identity provider to users, but what if a developer needs the same sign on outside of “browser land”?