The project 'Simple Access to Cultural Heritage Assets' (SACHA) is a joint venture with the Austrian Centre for Digital Humanities (ACDH) of the Austrian Academy of Sciences. It aims to provide scientists easier access to data of importance for cultural studies.
You can use this IIIF interface to view images and create collections.
The API documentation is available here
Create a private collection
Create your own collections using SACHA!
You can find and view your own, private (visible only to you) collections on your user page.