PSN is intended to be extended by modules. PSN comes with built-in modules which reside in the plugin’s subdirectory “modules”. Custom modules can be uploaded via the plugin’s Module Manager in the Service section. The Module Manager scans for custom modules in a subdirectory of the upload path called “post-status-notifier”. If you upload a valid custom module, the Module Manager will automatically copy it to this destination and list it as an installed module.