Provide “/callback” endpoint in the Web API the same way it is already provided in the Bridge HTTP-API.
Allow to register public (https) web services to be notified on lock/door state changes.
Enable web services to trigger actions in realtime following lock/door state changes instead of having to poll “/smartlock” every minute for the status.
Nuki callback notifies webservice that door is unlocked, webservice immediately turns on all Philips Hue lights with minimal delay.
Nuki callback notifies webservice that door is opened, webservice sends alarm notification if all household members have status “away from home”.