Subject to certain limitations, you can connect a number of Atlassian applications to a single JIRA application for centralized user management.
When to use this option: You can connect to a server running Jira 4.3 or later, Jira Software 7.0 or later, Jira Core 7.0 or later, or Jira Service Management (formerly Jira Service Desk) 3.0 or later. Choose this option as an alternative to Atlassian Crowd, for simple configurations with a limited number of users.