The HTML file format stores data in the HTML format. Converting to XLSX produces a spreadsheet file that stores cell values, formulas, formatting, and charts as zipped XML, the default format for Microsoft Excel 2007 and later. This extracts structured tabular data from the document into an editable spreadsheet format. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. This makes XLSX 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.