SK1 is a document format: it stores data in the SK1 format. HDR is a document format that stores data in the HDR format. This conversion changes the file's encoding, compression method, and supported feature set. Text content, headings, and basic formatting are transferred; complex features such as macros or embedded objects may not translate fully. 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.