Gembox.spreadsheet.dll

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

// Style a header var headerStyle = new CellStyle

var worksheet = reader.Worksheets[0]; foreach (var row in worksheet.Rows) // Process row by row without holding entire file in RAM Console.WriteLine(row.Cells[0].Value); gembox.spreadsheet.dll

HorizontalAlignment = HorizontalAlignmentStyle.Center, FillPattern = FillPatternStyle.Solid, FillPatternForegroundColor = SpreadsheetColor.FromName(ColorName.DarkBlue), FontColor = SpreadsheetColor.FromName(ColorName.White) ; worksheet.Cells.GetSubrange("A1:D1").Style = headerStyle;

A unique feature of this DLL is direct HTML rendering: workbook

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

worksheet.Cells[1, 0].Value = "Widget"; worksheet.Cells[1, 1].Value = 10; worksheet.Cells[1, 2].Value = 5.99; worksheet.Cells[1, 3].SetFormula("=B2*C2"); For truly massive files (500k+ rows)

// Add data worksheet.Cells[0, 0].Value = "Product"; worksheet.Cells[0, 1].Value = "Qty"; worksheet.Cells[0, 2].Value = "Price"; worksheet.Cells[0, 3].Value = "Total";