EPUB is a ebook format: it packages HTML, CSS, and images in a zipped OPS container as an ISO-standardised ebook format that reflows text to fit any screen width. PEF is a document format that stores data in the PEF format. This converts the reflowable ebook layout into a fixed-page document format. 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 PEF natively or when the target platform only accepts PEF. 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.