The Office Open XML Spreadsheet format stores cell values, formulas, formatting, and charts as zipped XML, the default format for Microsoft Excel 2007 and later. Converting to WEBP produces a image file that supports both lossy and lossless encoding with transparency and animation, typically 25-35% smaller than equivalent JPEG or PNG files. This conversion changes the file's encoding, compression method, and supported feature set. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. This makes WEBP the practical choice when the destination system requires it or when the original format is not supported by the target application. 1converter runs this conversion on the server: your file is uploaded encrypted over HTTPS, converted using trusted open-source libraries, and the output is held for 24 hours before automatic deletion.