Overview

• small codebase, easy to see in minutes that it's safe to run on your server
• no third party dependencies for the same reason
• no support for parsing as that's inherently risky on a sensitive server
• .xlsx only

Examples

Generate a basic report

Shows adding various cell data types, a frozen header row, per-column date and currency formats, color and font style formatting.

var book = new XlWorkbook();
var sheet = new XlSheet();
book.Sheets.Add(sheet);
sheet.FreezeRows = 1;
sheet.Columns[1].Style = XlStyle.New().Fmt(XlFmt.LocaleDate);
sheet.Columns[2].Width = 30;
sheet.Columns[2].Style = XlStyle.New().Align(XlHorz.Center).Font(bold: true);
sheet.Columns[3].Style = XlStyle.New().Fmt(XlFmt.AccountingGbp);
sheet.WriteSheet = sw =>
{
    sw.StartRow(XlStyle.New().Color("FFFFFF", "008800").BorderB(XlBorder.Medium).Align(XlVert.Center), height: 32);
    sw.AddCell("Date");
    sw.AddCell("Centered");
    sw.AddCell("Total");
    for (int i = 0; i < 20; i++)
    {
        sw.StartRow();
        sw.AddCell(DateTime.Today);
        sw.AddCell("Test entry");
        sw.AddCell(1047.25);
    }
};
book.Save("report.xlsx");

Workbook global styling

var book = new XlWorkbook();
book.Style.Mod().Font("Tahoma", 14);

(or assign a new style to book.Style but it must not omit anything, so it's easier to Mod()ify the default style in-place)

Saving options

book.Save(@"C:\Path\to\file.xlsx");

book.Save(response.Stream);

byte[] xlsx = book.SaveToArray();

Skip rows or columns

sheet.WriteSheet = sw =>
{
    sw.AddCell("Foo");       // writes to R1 C1
    sw.AddCell("Foo");       // writes to R1 C2
    sw.AddCell(7, "Foo");    // writes to R1 C7 - skipped cells are not written to xlsx

    sw.AddCell(4, 2, "Foo"); // writes to R4 C2 - skipped rows are not written to xlsx
                             // calling StartRow is optional; AddCell directly to R4 is OK

    sw.StartRow(9);
    sw.AddCell("Foo");       // writes to R9 C1

    sw.AddCell(8, 1, "Foo"); // exception - writes must be in row->column order
};

Features

• cell data types: strings, numbers, bools, dates
• apply styling to the whole workbook, whole row/column, or individual cells
• styling support for: font, fill, alignment, border, data format
• styling is additive, e.g. set font size globally, fill for a row, border for a column, and bold for a cell, and all will apply
• add multiple sheets; specify active sheet
• freeze columns/rows
• created/modified metadata

Performance

• unstyled 100,000 rows 100 cells each: 5.5 seconds (SwiftExcel manages 3 seconds)
• minimal RAM usage as sheet data is written to the output on-the-fly (16MB peak for the above example)
• with styling applied, performance drops very approximately up to 4x for the heaviest styling

Styling limitations:

• only basic font styling: family, size, color, bold, italic
• no rich text in cells
• solid color fills only
• no support for themes or palette colors - RGB/ARGB only
• no column-spanning styles
• no cell merging
• no diagonal borders
• whole-workbook style doesn't support fill or border (Excel limitation)
• no conditional formatting

Other limitations:

• this is a write-only library with no support for reading Excel files
• no formulas
• no data filters
• no charts, no images, no embeds
• no revision history, no notes, no comments
• no VBA
• no built-in support for writing sheet data out-of-order
• no support for sharedStrings for better compression of repetitive cells
• can't position cursor within the sheet or select a range
• no support for .xls
• not much documentation