Built in user managers
FtpServer comes with three different user managers:
Custom User Manager
You can write your own user manager to integrate it with your existing applications. Your custom user manager should implement org.apache.ftpserver.ftplet.UserManager interface. You also need to specify the fully qualified name of your custom user manager class in config.user-manager.class configuration parameter. All the configuration values under config.user-manager will be available to your user manager class.
User Manager UI
Users can be added, removed or modified using FTP server UI.