How do I create an Excel (.XLS and .XLSX) file in C# without installing Microsoft Office?

2008-09-30 c# .net excel file-io

How can I create an Excel spreadsheet with C# without requiring Excel to be installed on the machine that's running the code?


You actually might want to check out the interop classes available in C# (e.g. Microsoft.Office.Interop.Excel. You say no OLE (which this isn't), but the interop classes are very easy to use. Check out the C# Documentation here (Interop for Excel starts on page 1072 of the C# PDF).

You might be impressed if you haven't tried them.

Please be warned of Microsoft's stance on this:

Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment.

An extremely lightweight option may be to use HTML tables. Just create head, body, and table tags in a file, and save it as a file with an .xls extension. There are Microsoft specific attributes that you can use to style the output, including formulas.

I realize that you may not be coding this in a web application, but here is an example of the composition of an Excel file via an HTML table. This technique could be used if you were coding a console app, desktop app, or service.


Or, you could use the Interop ...

You can use OLEDB to create and manipulate Excel files. Check this: Reading and Writing Excel using OLEDB.

Typical example:

using (OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\temp\\test.xls;Extended Properties='Excel 8.0;HDR=Yes'"))
  OleDbCommand cmd = new OleDbCommand("CREATE TABLE [Sheet1] ([Column1] string, [Column2] string)", conn);

EDIT - Some more links:

You may want to take a look at GemBox.Spreadsheet.

They have a free version with all features but limited to 150 rows per sheet and 5 sheets per workbook, if that falls within your needs.

I haven't had need to use it myself yet, but does look interesting.

The Java open source solution is Apache POI. Maybe there is a way to setup interop here, but I don't know enough about Java to answer that.

When I explored this problem I ended up using the Interop assemblies.

You could consider creating your files using the XML Spreadsheet 2003 format. This is a simple XML format using a well documented schema.

Here's a way to do it with LINQ to XML, complete with sample code:

Quickly Import and Export Excel Data with LINQ to XML

It's a little complex, since you have to import namespaces and so forth, but it does let you avoid any external dependencies.

(Also, of course, it's VB .NET, not C#, but you can always isolate the VB .NET stuff in its own project to use XML Literals, and do everything else in C#.)

I agree about generating XML Spreadsheets, here's an example on how to do it for C# 3 (everyone just blogs about it in VB 9 :P)

Have you ever tried sylk?

We used to generate excelsheets in classic asp as sylk and right now we're searching for an excelgenerater too.

The advantages for sylk are, you can format the cells.

The various Office 2003 XML libraries avaliable work pretty well for smaller excel files. However, I find the sheer size of a large workbook saved in the XML format to be a problem. For example, a workbook I work with that would be 40MB in the new (and admittedly more tightly packed) XLSX format becomes a 360MB XML file.

As far as my research has taken me, there are two commercial packages that allow output to the older binary file formats. They are:

Neither are cheap (500USD and 800USD respectively, I think). but both work independant of Excel itself.

What I would be curious about is the Excel output module for the likes of I wonder if they can be ported from Java to .Net.

The commercial solution, SpreadsheetGear for .NET will do it.

You can see live ASP.NET (C# and VB) samples here and download an evaluation version here.

Disclaimer: I own SpreadsheetGear LLC

You can use ExcelXmlWriter.

It works fine.

I've just recently used FlexCel.NET and found it to be an excellent library! I don't say that about too many software products. No point in giving the whole sales pitch here, you can read all the features on their website.

It is a commercial product, but you get the full source if you buy it. So I suppose you could compile it into your assembly if you really wanted to. Otherwise it's just one extra assembly to xcopy - no configuration or installation or anything like that.

I don't think you'll find any way to do this without third-party libraries as .NET framework, obviously, does not have built in support for it and OLE Automation is just a whole world of pain.

A few options I have used:

If XLSX is a must: ExcelPackage is a good start but died off when the developer quit working on it. ExML picked up from there and added a few features. ExML isn't a bad option, I'm still using it in a couple of production websites.

For all of my new projects, though, I'm using NPOI, the .NET port of Apache POI. NPOI 2.0 (Alpha) also supports XLSX.

I've used with success the following open source projects:

  • ExcelPackage for OOXML formats (Office 2007)

  • NPOI for .XLS format (Office 2003). NPOI 2.0 (Beta) also supports XLSX.

Take a look at my blog posts:

Creating Excel spreadsheets .XLS and .XLSX in C#

NPOI with Excel Table and dynamic Chart

I also vote for GemBox.Spreadsheet.

Very fast and easy to use, with tons of examples on their site.

Took my reporting tasks on a whole new level of execution speed.

Some useful Excel automation in C# , u can find from the following link.



you can also use a third party library like Aspose.

This library has the benefit that it does not require Excel to be installed on your machine which would be ideal in your case.

If you are happy with the xlsx format, try my GitHub project, EPPlus. It started with the source from ExcelPackage, but today it's a total rewrite. It supports ranges, cell styling, charts, shapes, pictures, named ranges, AutoFilter and a lot of other stuff.

You can use a library called ExcelLibrary. It's a free, open source library posted on Google Code:


This looks to be a port of the PHP ExcelWriter that you mentioned above. It will not write to the new .xlsx format yet, but they are working on adding that functionality in.

It's very simple, small and easy to use. Plus it has a DataSetHelper that lets you use DataSets and DataTables to easily work with Excel data.

ExcelLibrary seems to still only work for the older Excel format (.xls files), but may be adding support in the future for newer 2007/2010 formats.

You can also use EPPlus, which works only for Excel 2007/2010 format files (.xlsx files). There's also NPOI which works with both.

There are a few known bugs with each library as noted in the comments. In all, EPPlus seems to be the best choice as time goes on. It seems to be more actively updated and documented as well.

Also, as noted by @АртёмЦарионов below, EPPlus has support for Pivot Tables and ExcelLibrary may have some support (Pivot table issue in ExcelLibrary)

Here are a couple links for quick reference:
ExcelLibrary - GNU Lesser GPL
EPPlus - GNU Lesser General Public License (LGPL)
NPOI - Apache License

Here some example code for ExcelLibrary:

Here is an example taking data from a database and creating a workbook from it. Note that the ExcelLibrary code is the single line at the bottom:

//Create the data set and table
DataSet ds = new DataSet("New_DataSet");
DataTable dt = new DataTable("New_DataTable");

//Set the locale for each
ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
dt.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;

//Open a DB connection (in this example with OleDB)
OleDbConnection con = new OleDbConnection(dbConnectionString);

//Create a query and fill the data table with the data from the DB
string sql = "SELECT Whatever FROM MyDBTable;";
OleDbCommand cmd = new OleDbCommand(sql, con);
OleDbDataAdapter adptr = new OleDbDataAdapter();

adptr.SelectCommand = cmd;

//Add the table to the data set

//Here's the easy part. Create the Excel worksheet from the data set
ExcelLibrary.DataSetHelper.CreateWorkbook("MyExcelFile.xls", ds);

Creating the Excel file is as easy as that. You can also manually create Excel files, but the above functionality is what really impressed me.

You can just write it out to XML using the Excel XML format and name it with .XLS extension and it will open with excel. You can control all the formatting (bold, widths, etc) in your XML file heading.

There is an example XML from Wikipedia.

If you're creating Excel 2007/2010 files give this open source project a try:

It provides an object oriented way to manipulate the files (similar to VBA) without dealing with the hassles of XML Documents. It can be used by any .NET language like C# and Visual Basic (VB).

ClosedXML allows you to create Excel 2007/2010 files without the Excel application. The typical example is creating Excel reports on a web server:

var workbook = new XLWorkbook();
var worksheet = workbook.Worksheets.Add("Sample Sheet");
worksheet.Cell("A1").Value = "Hello World!";

You can create nicely formatted Excel files using this library:
See below sample:

using (ExcelHelper helper = new ExcelHelper(TEMPLATE_FILE_NAME, GENERATED_FILE_NAME))
    helper.Direction = ExcelHelper.DirectionType.TOP_TO_DOWN;
    helper.CurrentSheetName = "Sheet1";
    helper.CurrentPosition = new CellRef("C3");

    //the template xlsx should contains the named range "header"; use the command "insert"/"name".

    //the template xlsx should contains the named range "sample1";
    //inside this range you should have cells with these values:
    //<name> , <value> and <comment>, which will be replaced by the values from the getSample()
    CellRangeTemplate sample1 = helper.CreateCellRangeTemplate("sample1", new List<string> {"name", "value", "comment"}); 
    helper.InsertRange(sample1, getSample());

    //you could use here other named ranges to insert new cells and call InsertRange as many times you want, 
    //it will be copied one after another;
    //even you can change direction or the current cell/sheet before you insert

    //typically you put all your "template ranges" (the names) on the same sheet and then you just delete it

where sample look like this:

private IEnumerable<List<object>> getSample()
    var random = new Random();

    for (int loop = 0; loop < 3000; loop++)
        yield return new List<object> {"test", DateTime.Now.AddDays(random.NextDouble()*100 - 50), loop};
} <= why not just use the built in power of windows, just install office on the server, any application that you install can be automated.

So much easier just use the native methods.

If it installed you can use it, this is the most awesome and under used feature in windows it was Dubbed COM back in the good old days, and it saves you tons of time and pain.

Or even easier just use the ref lib MS supplies -

Some 3rd party component vendors like Infragistics or Syncfusion provide very good Excel export capabilities that do not require Microsoft Excel to be installed.

Since these vendors also provide advanced UI grid components, these components are particularly handy if you want the style and layout of an excel export to mimic the current state of a grid in the user interface of your application.

If your export is intended to be executed server side with emphasis on the data to be exported and with no link to the UI, then I would go for one of the free open source options (e.g. ExcelLibrary).

I have previously been involved with projects that attempted to use server side automation on the Microsoft Office suite. Based on this experience I would strongly recommend against that approach.

Look at samples how to create Excel files.

There are examples in C# and VB.NET

It manages XSL XSLX and CSV Excel files.

public class GridViewExportUtil
    public static void Export(string fileName, GridView gv)
            "content-disposition", string.Format("attachment; filename={0}", fileName));
        HttpContext.Current.Response.ContentType = "application/ms-excel";

        using (StringWriter sw = new StringWriter())
            using (HtmlTextWriter htw = new HtmlTextWriter(sw))
                //  Create a form to contain the grid
                Table table = new Table();

                //  add the header row to the table
                if (gv.HeaderRow != null)

                //  add each of the data rows to the table
                foreach (GridViewRow row in gv.Rows)

                //  add the footer row to the table
                if (gv.FooterRow != null)

                //  render the table into the htmlwriter

                //  render the htmlwriter into the response

    /// <summary>
    /// Replace any of the contained controls with literals
    /// </summary>
    /// <param name="control"></param>
    private static void PrepareControlForExport(Control control)
        for (int i = 0; i < control.Controls.Count; i++)
            Control current = control.Controls[i];
            if (current is LinkButton)
                control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text));
            else if (current is ImageButton)
                control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText));
            else if (current is HyperLink)
                control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text));
            else if (current is DropDownList)
                control.Controls.AddAt(i, new LiteralControl((current as DropDownList).SelectedItem.Text));
            else if (current is CheckBox)
                control.Controls.AddAt(i, new LiteralControl((current as CheckBox).Checked ? "True" : "False"));

            if (current.HasControls())

Hi this solution is to export your grid view to your excel file it might help you out

And what about using Open XML SDK 2.0 for Microsoft Office?

A few benefits:

  • Doesn't require Office installed
  • Made by Microsoft = decent MSDN documentation
  • Just one .Net dll to use in project
  • SDK comes with many tools like diff, validator, etc


Just want to add another reference to a third party solution that directly addresses your issue:

(Disclaimer: I work for SoftArtisans, the company that makes OfficeWriter)

Here's a completely free C# library, which lets you export from a DataSet, DataTable or List<> into a genuine Excel 2007 .xlsx file, using the OpenXML libraries:

Full source code is provided - free of charge - along with instructions, and a demo application.

After adding this class to your application, you can export your DataSet to Excel in just one line of code:

CreateExcelFile.CreateExcelDocument(myDataSet, "C:\\Sample.xlsx");

It doesn't get much simpler than that...

And it doesn't even require Excel to be present on your server.

I am using following code for create excel 2007 file which create the file and write in that file but when i open the file but it give me error that exel cannot open the file bcz file might be coruupted or extension of the file is not compatible. but if i used .xls for file it work fines

for (int i = 0; i < TotalFile; i++)
    if (innerloop == SplitSize)
        for (int j = 0; j < SplitSize; j++)
            string strContact = DSt.Tables[0].Rows[i * SplitSize + j][0].ToString();
        string strExcel = strFileName + "_" + i.ToString() + ".xlsx";
                         File.WriteAllLines(strExcel, Contact.ToArray());

also refer link

I have written a simple code to export dataset to excel without using excel object by using System.IO.StreamWriter.

Below is the code which will read all tables from dataset and write them to sheets one by one. I took help from this article.

public static void exportToExcel(DataSet source, string fileName)
        const string endExcelXML = "</Workbook>";
        const string startExcelXML = "<xml version>\r\n<Workbook " +
                 "xmlns=\"urn:schemas-microsoft-com:office:spreadsheet\"\r\n" +
                 " xmlns:o=\"urn:schemas-microsoft-com:office:office\"\r\n " +
                 "xmlns:x=\"urn:schemas-    microsoft-com:office:" +
                 "excel\"\r\n xmlns:ss=\"urn:schemas-microsoft-com:" +
                 "office:spreadsheet\">\r\n <Styles>\r\n " +
                 "<Style ss:ID=\"Default\" ss:Name=\"Normal\">\r\n " +
                 "<Alignment ss:Vertical=\"Bottom\"/>\r\n <Borders/>" +
                 "\r\n <Font/>\r\n <Interior/>\r\n <NumberFormat/>" +
                 "\r\n <Protection/>\r\n </Style>\r\n " +
                 "<Style ss:ID=\"BoldColumn\">\r\n <Font " +
                 "x:Family=\"Swiss\" ss:Bold=\"1\"/>\r\n </Style>\r\n " +
                 "<Style     ss:ID=\"StringLiteral\">\r\n <NumberFormat" +
                 " ss:Format=\"@\"/>\r\n </Style>\r\n <Style " +
                 "ss:ID=\"Decimal\">\r\n <NumberFormat " +
                 "ss:Format=\"0.0000\"/>\r\n </Style>\r\n " +
                 "<Style ss:ID=\"Integer\">\r\n <NumberFormat " +
                 "ss:Format=\"0\"/>\r\n </Style>\r\n <Style " +
                 "ss:ID=\"DateLiteral\">\r\n <NumberFormat " +
                 "ss:Format=\"mm/dd/yyyy;@\"/>\r\n </Style>\r\n " +
                 "</Styles>\r\n ";
        System.IO.StreamWriter excelDoc = null;
        excelDoc = new System.IO.StreamWriter(fileName);

        int sheetCount = 1;
        foreach (DataTable table in source.Tables)
            int rowCount = 0;
            excelDoc.Write("<Worksheet ss:Name=\"" + table.TableName + "\">");
            for (int x = 0; x < table.Columns.Count; x++)
                excelDoc.Write("<Cell ss:StyleID=\"BoldColumn\"><Data ss:Type=\"String\">");
            foreach (DataRow x in table.Rows)
                //if the number of rows is > 64000 create a new page to continue output
                if (rowCount == 64000)
                    rowCount = 0;
                    excelDoc.Write(" </Worksheet>");
                    excelDoc.Write("<Worksheet ss:Name=\"" + table.TableName + "\">");
                excelDoc.Write("<Row>"); //ID=" + rowCount + "
                for (int y = 0; y < table.Columns.Count; y++)
                    System.Type rowType;
                    rowType = x[y].GetType();
                    switch (rowType.ToString())
                        case "System.String":
                            string XMLstring = x[y].ToString();
                            XMLstring = XMLstring.Trim();
                            XMLstring = XMLstring.Replace("&", "&");
                            XMLstring = XMLstring.Replace(">", ">");
                            XMLstring = XMLstring.Replace("<", "<");
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                           "<Data ss:Type=\"String\">");
                        case "System.DateTime":
                            //Excel has a specific Date Format of YYYY-MM-DD followed by  
                            //the letter 'T' then hh:mm:sss.lll Example 2005-01-31T24:01:21.000
                            //The Following Code puts the date stored in XMLDate 
                            //to the format above
                            DateTime XMLDate = (DateTime)x[y];
                            string XMLDatetoString = ""; //Excel Converted Date
                            XMLDatetoString = XMLDate.Year.ToString() +
                                 "-" +
                                 (XMLDate.Month < 10 ? "0" +
                                 XMLDate.Month.ToString() : XMLDate.Month.ToString()) +
                                 "-" +
                                 (XMLDate.Day < 10 ? "0" +
                                 XMLDate.Day.ToString() : XMLDate.Day.ToString()) +
                                 "T" +
                                 (XMLDate.Hour < 10 ? "0" +
                                 XMLDate.Hour.ToString() : XMLDate.Hour.ToString()) +
                                 ":" +
                                 (XMLDate.Minute < 10 ? "0" +
                                 XMLDate.Minute.ToString() : XMLDate.Minute.ToString()) +
                                 ":" +
                                 (XMLDate.Second < 10 ? "0" +
                                 XMLDate.Second.ToString() : XMLDate.Second.ToString()) +
                            excelDoc.Write("<Cell ss:StyleID=\"DateLiteral\">" +
                                         "<Data ss:Type=\"DateTime\">");
                        case "System.Boolean":
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                        "<Data ss:Type=\"String\">");
                        case "System.Int16":
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            excelDoc.Write("<Cell ss:StyleID=\"Integer\">" +
                                    "<Data ss:Type=\"Number\">");
                        case "System.Decimal":
                        case "System.Double":
                            excelDoc.Write("<Cell ss:StyleID=\"Decimal\">" +
                                  "<Data ss:Type=\"Number\">");
                        case "System.DBNull":
                            excelDoc.Write("<Cell ss:StyleID=\"StringLiteral\">" +
                                  "<Data ss:Type=\"String\">");
                            throw (new Exception(rowType.ToString() + " not handled."));
            excelDoc.Write(" </Worksheet>");


OpenXML is also a good alternative that helps avoid installing MS Excel on Server.The Open XML SDK 2.0 provided by Microsoft simplifies the task of manipulating Open XML packages and the underlying Open XML schema elements within a package. The Open XML Application Programming Interface (API) encapsulates many common tasks that developers perform on Open XML packages.

Check this out OpenXML: Alternative that helps avoid installing MS Excel on Server

Syncfusion Essential XlsIO can do this. It has no dependency on Microsoft office and also has specific support for different platforms.

Code sample:

//Creates a new instance for ExcelEngine.
ExcelEngine excelEngine = new ExcelEngine();
//Loads or open an existing workbook through Open method of IWorkbooks
IWorkbook workbook = excelEngine.Excel.Workbooks.Open(fileName);
//To-Do some manipulation|
//To-Do some manipulation
//Set the version of the workbook.
workbook.Version = ExcelVersion.Excel2013;
//Save the workbook in file system as xlsx format

The whole suite of controls is available for free through the community license program if you qualify (less than 1 million USD in revenue). Note: I work for Syncfusion.

The simplest and fastest way to create an Excel file from C# is to use the Open XML Productivity Tool. The Open XML Productivity Tool comes with the Open XML SDK installation. The tool reverse engineers any Excel file into C# code. The C# code can then be used to re-generate that file.

An overview of the process involved is:

  1. Install the Open XML SDK with the tool.
  2. Create an Excel file using the latest Excel client with desired look. Name it DesiredLook.xlsx.
  3. With the tool open DesiredLook.xlsx and click the Reflect Code button near the top. enter image description here
  4. The C# code for your file will be generated in the right pane of the tool. Add this to your C# solution and generate files with that desired look.

As a bonus, this method works for any Word and PowerPoint files. As the C# developer, you will then make changes to the code to fit your needs.

I have developed a simple WPF app on github which will run on Windows for this purpose. There is a placeholder class called GeneratedClass where you can paste the generated code. If you go back one version of the file, it will generate an excel file like this:

enter image description here

If you make data table or datagridview from the code you can save all data using this simple method.this method not recomended but its working 100%, even you are not install MS Excel in your computer.

  SaveFileDialog saveFileDialog1 = new SaveFileDialog();
  saveFileDialog1.Filter = "Excel Documents (*.xls)|*.xls";
  saveFileDialog1.FileName = "Employee Details.xls";
  if (saveFileDialog1.ShowDialog() == DialogResult.OK)
  string fname = saveFileDialog1.FileName;
  StreamWriter wr = new StreamWriter(fname);
  for (int i = 0; i <DataTable.Columns.Count; i++)
  wr.Write(DataTable.Columns[i].ToString().ToUpper() + "\t");

  //write rows to excel file
  for (int i = 0; i < (DataTable.Rows.Count); i++)
  for (int j = 0; j < DataTable.Columns.Count; j++)
  if (DataTable.Rows[i][j] != null)
  wr.Write(Convert.ToString(getallData.Rows[i][j]) + "\t");
   //go to next line
   //close file
   catch (Exception)
    MessageBox.Show("Error Create Excel Sheet!");

Some time ago, I created a DLL on top of NPOI. It's very simple to use it:

IList<DummyPerson> dummyPeople = new List<DummyPerson>();
//Add data to dummyPeople...
IExportEngine engine = new ExcelExportEngine();
MemoryStream memory = engine.Export();

You could read more about it on here.

By the way, is 100% open source. Feel free to use, edit and share ;)

One really easy option which is often overlooked is to create a .rdlc report using Microsoft Reporting and export it to excel format. You can design it in visual studio and generate the file using:

localReport.Render("EXCELOPENXML", null, ((name, ext, encoding, mimeType, willSeek) => stream = new FileStream(name, FileMode.CreateNew)), out warnings);

You can also export it do .doc or .pdf, using "WORDOPENXML" and "PDF" respectively, and it's supported on many different platforms such as ASP.NET and SSRS.

It's much easier to make changes in a visual designer where you can see the results, and trust me, once you start grouping data, formatting group headers, adding new sections, you don't want to mess with dozens of XML nodes.

To save xls into xlsx format, we just need to call SaveAs method from Microsoft.Office.Interop.Excel library. This method will take around 16 parameters and one of them is file format as well.

Microsoft document: Here SaveAs Method Arguments

The object we need to pass is like

wb.SaveAs(filename, 51, System.Reflection.Missing.Value,
System.Reflection.Missing.Value, false, false, 1,1, true, 
System.Reflection.Missing.Value, System.Reflection.Missing.Value, System.Reflection.Missing.Value)

Here, 51 is is enumeration value for XLSX

For SaveAs in different file formats you can refer the xlFileFormat

check this out no need for third party libraries you can simply export datatable data to excel file using this

var dt = "your code for getting data into datatable";
            Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", DateTime.Now.ToString("yyyy-MM-dd")));
            Response.ContentType = "application/";
            string tab = "";
            foreach (DataColumn dataColumn in dt.Columns)
                Response.Write(tab + dataColumn.ColumnName);
                tab = "\t";
            int i;
            foreach (DataRow dataRow in dt.Rows)
                tab = "";
                for (i = 0; i < dt.Columns.Count; i++)
                    Response.Write(tab + dataRow[i].ToString());
                    tab = "\t";

How to create an Excel (.xslx) file using C# on OneDrive without installing Microsoft Office

The Microsoft Graph API provides File and Excel APIs for creating and modifying Excel files stored in OneDrive for both enterprise and consumer accounts. The Microsoft.Graph NuGet package provides many interfaces for working with the File and Excel APIs.

  Name = "myExcelFile.xslx",
  File = new Microsoft.Graph.File()

// Create an empty file in the user's OneDrive.
var excelWorkbookDriveItem = await graphClient.Me.Drive.Root.Children.Request().AddAsync(excelWorkbook);

// Add the contents of a template Excel file.
DriveItem excelDriveItem;
using (Stream ms = ResourceHelper.GetResourceAsStream(ResourceHelper.ExcelTestResource))
    //Upload content to the file. ExcelTestResource is an empty template Excel file.
    excelDriveItem = await graphClient.Me.Drive.Items[excelWorkbookDriveItem.Id].Content.Request().PutAsync<DriveItem>(ms);

At this point, you now have an Excel file created in the user (enterprise or consumer) or group's OneDrive. You can now use the Excel APIs to make changes to the Excel file without using Excel and without needing to understand the Excel XML format.

You can try my SwiftExcel library. This library writes directly to the file, so it is very efficient. For example you can write 100k rows in few seconds without any memory usage.

Here is a simple example of usage:

using (var ew = new ExcelWriter("C:\\temp\\test.xlsx"))
    for (var row = 1; row <= 10; row++)
        for (var col = 1; col <= 5; col++)
            ew.Write($"row:{row}-col:{col}", col, row);