Merge SPREADSHEETML to XLTX Online for Free. Free Online SPREADSHEETML to XLTX Merger. Merge SPREADSHEETML to Word, Excel, PPTX, PDF, JPG, HTML, ODS, SVG, XPS and more.... Upload your files, call Workbook.Combine method for merging...import Workbook workbook = Workbook( "Input.xlsx" ) workbook.combine(Workbook(...