NEF is a image format: it stores data in the NEF format. SK1 is a document format that stores data in the SK1 format. This embeds the raster image inside a document container, fixing its dimensions on the page. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. Converting between these two formats is common when the source application does not support SK1 natively or when the target platform only accepts SK1. 1converter processes this conversion server-side using open-source tools. Files are transferred over HTTPS, converted on secure cloud servers, and automatically deleted after 24 hours.