Gembox.spreadsheet.dll May 2026

workbook.Save("Report.xlsx"); For truly massive files (500k+ rows), use the LoadOptions to stream data:

var workbook = new ExcelFile(); var worksheet = workbook.Worksheets.Add("Sales Report"); gembox.spreadsheet.dll

// Style a header var headerStyle = new CellStyle workbook

HorizontalAlignment = HorizontalAlignmentStyle.Center, FillPattern = FillPatternStyle.Solid, FillPatternForegroundColor = SpreadsheetColor.FromName(ColorName.DarkBlue), FontColor = SpreadsheetColor.FromName(ColorName.White) ; worksheet.Cells.GetSubrange("A1:D1").Style = headerStyle; For truly massive files (500k+ rows)