 <p>FIM doesn't do authentication. Instead, it does the user management and synchronization piece.</p> <p>You would want to integrate with one of the directories FIM is synchronizing. If your app is within the firewall, you would typically use AD or LDAP (Kerberos-based). If your app is outside of the firewall, you would typically use Azure Active Directory or another SAML-based Identity Provider.</p>