FB2 is a ebook format: it stores data in the FB2 format. HDR is a document format that stores data in the HDR 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 HDR natively or when the target platform only accepts HDR. 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.