PEF is a document format: it stores data in the PEF format. MOBI is a ebook format that stores reflowable text in the Mobipocket format originally designed for Amazon Kindle devices, now largely superseded by KFX. This reformats the fixed-layout document into a reflowable ebook that adapts to screen size. 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 MOBI natively or when the target platform only accepts MOBI. 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.