Change effective on 30 August 2016
Heroku Enterprise Administrators can choose to deny OAuth access to org-owned resources from all non-Heroku products and services. In the settings tab of the org, administrators will find a toggle control where they can switch off third-party OAuth access to the Heroku Platform API. Members of the org can still OAuth with Heroku, but org owned resources will not be accessible.
This feature can be a useful part of a company’s comprehensive plan to meet internal and external information access compliance regulations.
For more information see the Heroku Enterprise documentation.