Hi Jeff,
Thank you for your interest in Essential XlsIO.
Essential XlsIO is a .NET library that can read and write Microsoft Excel files (BIFF 8 format and SpreadsheetML). You can take an excel file as input and save it in either BIFF 8 or SpreadsheetML format. You can refer the following link for more details:
http://www2.syncfusion.com/ug/Default.aspx##Essential%20Studio.chm/XlsIOBase/IntroducingEssentialExcelrw.htmlKindly let me know if you have any other questions.
Thanks,
Melba