The Notifier OpenAPI specification is a standard for describing REST-compliant application programming interfaces (API). With the OpenAPI, you can connect your user-developed app to the Notifier and access the interfaces of the Notifier. In this way, for example, notifications can be triggered from other apps and displayed in the Notifier.
Notifications outside of the Notifier can also be accepted via the OpenAPI interface. If this is the case and the user is not registered in the Notifier, the accepted notification is marked in the Notifier with the respective email address:
You can find all available routes for the Notifier by clicking the 
icon in the title bar under "API Documentation".
You can find additional information on how to implement Notifier OpenAPI here: Notifier OpenAPI implementation.