I need to convert xlsx file to xml

Question

To do so I have used the Aspose.cells nuget package but this library is for evaluation only. Workbook workbook = new Workbook("Book1.xlsx");

//Load your source workbook
Workbook workbook = new Workbook("Book1.xlsx");

//Save as Excel 2003 Spreadsheet XML workbook.Save("Spreadsheet.xml");

//Save as plain XML data XmlSaveOptions xmlSaveOptions = new XmlSaveOptions(); workbook.Save("data.xml", xmlSaveOptions);

So the library is converting like above.

but I am searching for a free library or any other method. I am doing this in C#. So please help me with this.