Adding the concept of curation to the world of IIIF will enrich user's experience for expressing and sharing their interests and creativity. We define curation as a user-generated collection of the whole or part of images across multiple sources, typically under a theme, and optionally with a meaningful ordering. The idea of curation, however, is excluded from the current IIIF APIs, because IIIF has evolved from the necessity of accessing a book, whose structure is defined by a physical object. The structure of curation, on the other hand, can be defined by users where the only constraint is their imagination. To introduce this flexibility to IIIF, we decided to design a new API called Curation API that allows more fine-grained units of distribution, such as ranges and canvases. We have been developing an open source software implementation, IIIF Curation Viewer, for studying the applicability of the specification and demonstrating the value of curations. We also have been developing an open source software, JSONkeeper, to store a curation in JSON-LD format, and to provide curations for search and discovery services. At present, IIIF Curation Viewer has functionality to add metadata to curated canvases, which will be used in the future for searching interesting canvases from diverse viewpoints. We also plan to explore curation's inter-linking structure across multiple manifests, which leads to taking advantage of the linked data aspect of IIIF. Finally, as the summary of our activities at Center for Open Data in the Humanities (CODH), we introduce other specifications we proposed, namely Timeline API and Cursor API, designed for scientific applications in mind.