Systems, methods and computer program products for controlling access to an organization's data in a multitenant environment are provided. An organization hierarchy is defined at a multitenant platform, the organization hierarchy comprising an organization and a plurality of sites owned by the organization, each of the plurality of sites representing a data isolation boundary for the organization's data. The sites are associated with subscriptions to applications of the multitenant platform. The organization can designate user partitions within the sites, each user partition designating a corresponding set of site users and a corresponding authentication service. The multitenant platform enables access to each subscription of a site only if a site user is authenticated by the authentication service designated in the user partition corresponding to the site user.