Class Libraries & REST APIs for the developers To manipulate & process Files from Word, Excel, PowerPoint, Visio, PDF, CAD & several other categories in Web, DeskTop or Mobile apps. Develop & deploy on Windows, Linux, MacOS & Android platforms....OpenOffice spreadsheet file (so XLS, XLSX, XLSM, XLSB, ODS and so on)...C# string filePath = "source.xlsx" ; //Load your source workbook...