If you are talking about the Bridge HTTP API you should find it at the Nuki Bridge infos:
Open Manage Bridge from the Nuki App menu and connect to the bridge:
Tap on the Bridge icon to activate the HTTP API and get the needed values:
If you can open up that page but still don’t see any info please check your Bridge ID. If it starts with 14 or higher please check out Nuki Bridge hardware revision.
All API documentation in general can be found at: