The Open Image Collections is a collection of digital image sources suitable for teaching, learning and research. Sources include museum digital collections, stock images, photo archives, design resources and image search engines. The project is started by Hedren Sum, a librarian at Nanyang Technological University. The 'Openness' of each image has been labeled at the webpage.
The Smithsonian Open Access has nearly 3 million 2D and 3D digital items across the Smithsonian’s 19 museums, nine research centers, libraries, archives, and the National Zoo.
Users can access open access metadata and register for an API key via the Smithsonian’s public API hosted on api.data.gov.
The collections in Harvard Art Museums include approximately 250,000 objects in all media, featuring European & American art from the Middle Ages to the present day.
The Harvard Art Museums provide a REST-style service designed for developers who wish to explore and integrate the museums’ collections in their projects. The documentation of the Harvard Art Museums API can be found here.
MoMA's evolving collection contains almost 200,000 works from around the world spanning the last 150 years.
The GitHub Page of MoMA provides datasets that contain the metadata of each artwork and artist. The datasets are updated monthly.