Create, read, and edit Excel files in Blazor

24 Jul 202424 minutes to read

Syncfusion Excel library for Blazor platform can be used to create, read, edit Excel files. This also convert Excel files to PDF.

Create a simple Excel report in Blazor Server-Side application

The below steps illustrates the creation of a simple Invoice formatted Excel document in Blazor Server-Side application.

Step 1: Create a new C# Blazor Server-Side application project. Select Blazor App from the template and click the Next button.

Create Blazor Server Side application in Visual Studio

Step 2: Now, the project configuration window will popup. Click Create button to create a new project with the required project name.

Create Blazor Server Side application in Visual Studio

Step 3: Choose Blazor Server App and click Create button to create a new Blazor Server-Side application for .NET Core 3.0.0-preview9.

Create Blazor Server Side application in Visual Studio

Step 4: Install the Syncfusion.XlsIO.Net.Core NuGet package as reference to your Blazor application from NuGet.org.

Install Syncfusion.XlsIO.Net.Core Nuget Package

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components.

Step 5: Create a razor file with name as Excel under Pages folder and include the following namespaces in the file.

C#
@page "/Excel"
   @using System.IO;
   @using ServerSideApplication;
   @inject ServerSideApplication.Data.ExcelService service
   @inject Microsoft.JSInterop.IJSRuntime JS

Step 6: Add the following code to create a new button.

CSHTML
<h2>Syncfusion Excel library (Essential XlsIO)</h2>
   <p>Syncfusion Excel library (Essential XlsIO)  is a Blazor Excel library used to create, read, edit, and convert Excel files in your applications without Microsoft Office dependencies.</p>
   <button class="btn btn-primary" @onclick="@CreateDocument">Create Document</button>

Step 7: Add the following code in Excel.razor file to create and download the Excel document.

C#
@code {
       MemoryStream excelStream;
   
       /// <summary>
       /// Create and download the Excel document
       /// </summary>
       protected async void CreateDocument()
       {
           excelStream = service.CreateExcel();
           await JS.SaveAs("Sample.xlsx", excelStream.ToArray());
       }
   }

Step 8: Create a new cs file with name as ExcelService under Data folder and include the following namespaces in the file.

C#
@using Syncfusion.XlsIO;
   @using Syncfusion.Drawing;
   @using System.IO;

Step 9: Create a new MemoryStream method with name as CreateExcel and include the following code snippet to create a simple Invoice formatted Excel document in Blazor Server-Side application.

C#
//Create an instance of ExcelEngine
   using (ExcelEngine excelEngine = new ExcelEngine())
   {
     IApplication application = excelEngine.Excel;
     application.DefaultVersion = ExcelVersion.Xlsx;
     
     //Create a workbook
     IWorkbook workbook = application.Workbooks.Create(1);
     IWorksheet worksheet = workbook.Worksheets[0];
     
     //Add a picture
     FileStream imageStream = new FileStream("AdventureCycle.png", FileMode.Open);
     Image image = Image.FromStream(imageStream);
     IPictureShape shape = worksheet.Pictures.AddPicture(1, 1, image, 20, 20);
     
     //Disable gridlines in the worksheet
     worksheet.IsGridLinesVisible = false;
     
     //Enter values to the cells from A3 to A5
     worksheet.Range["A3"].Text = "46036 Michigan Ave";
     worksheet.Range["A4"].Text = "Canton, USA";
     worksheet.Range["A5"].Text = "Phone: +1 231-231-2310";
     
     //Make the text bold
     worksheet.Range["A3:A5"].CellStyle.Font.Bold = true;
     
     //Merge cells
     worksheet.Range["D1:E1"].Merge();
     
     //Enter text to the cell D1 and apply formatting
     worksheet.Range["D1"].Text = "INVOICE";
     worksheet.Range["D1"].CellStyle.Font.Bold = true;
     worksheet.Range["D1"].CellStyle.Font.RGBColor = Color.FromArgb(42, 118, 189);
     worksheet.Range["D1"].CellStyle.Font.Size = 35;
     
     //Apply alignment in the cell D1
     worksheet.Range["D1"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight;
     worksheet.Range["D1"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter values to the cells from D5 to E8
     worksheet.Range["D5"].Text = "INVOICE#";
     worksheet.Range["E5"].Text = "DATE";
     worksheet.Range["D6"].Number = 1028;
     worksheet.Range["E6"].Value = "12/31/2018";
     worksheet.Range["D7"].Text = "CUSTOMER ID";
     worksheet.Range["E7"].Text = "TERMS";
     worksheet.Range["D8"].Number = 564;
     worksheet.Range["E8"].Text = "Due Upon Receipt";
     
     //Apply RGB backcolor to the cells from D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["D7:E7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply known colors to the text in cells D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["D7:E7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Make the text as bold from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.Font.Bold = true;
     
     //Apply alignment to the cells from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D5:E5"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D7:E7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D6:E6"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter value and applying formatting in the cell A7
     worksheet.Range["A7"].Text = "  BILL TO";
     worksheet.Range["A7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["A7"].CellStyle.Font.Bold = true;
     worksheet.Range["A7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Apply alignment
     worksheet.Range["A7"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["A7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     
     //Enter values in the cells A8 to A12
     worksheet.Range["A8"].Text = "Steyn";
     worksheet.Range["A9"].Text = "Great Lakes Food Market";
     worksheet.Range["A10"].Text = "20 Whitehall Rd";
     worksheet.Range["A11"].Text = "North Muskegon,USA";
     worksheet.Range["A12"].Text = "+1 231-654-0000";
     
     //Create a Hyperlink for e-mail in the cell A13
     IHyperLink hyperlink = worksheet.HyperLinks.Add(worksheet.Range["A13"]);
     hyperlink.Type = ExcelHyperLinkType.Url;
     hyperlink.Address = "Steyn@greatlakes.com";
     hyperlink.ScreenTip = "Send Mail";
     
     //Merge column A and B from row 15 to 22
     worksheet.Range["A15:B15"].Merge();
     worksheet.Range["A16:B16"].Merge();
     worksheet.Range["A17:B17"].Merge();
     worksheet.Range["A18:B18"].Merge();
     worksheet.Range["A19:B19"].Merge();
     worksheet.Range["A20:B20"].Merge();
     worksheet.Range["A21:B21"].Merge();
     worksheet.Range["A22:B22"].Merge();
     
     //Enter details of products and prices
     worksheet.Range["A15"].Text = "  DESCRIPTION";
     worksheet.Range["C15"].Text = "QTY";
     worksheet.Range["D15"].Text = "UNIT PRICE";
     worksheet.Range["E15"].Text = "AMOUNT";
     worksheet.Range["A16"].Text = "Cabrales Cheese";
     worksheet.Range["A17"].Text = "Chocos";
     worksheet.Range["A18"].Text = "Pasta";
     worksheet.Range["A19"].Text = "Cereals";
     worksheet.Range["A20"].Text = "Ice Cream";
     worksheet.Range["C16"].Number = 3;
     worksheet.Range["C17"].Number = 2;
     worksheet.Range["C18"].Number = 1;
     worksheet.Range["C19"].Number = 4;
     worksheet.Range["C20"].Number = 3;
     worksheet.Range["D16"].Number = 21;
     worksheet.Range["D17"].Number = 54;
     worksheet.Range["D18"].Number = 10;
     worksheet.Range["D19"].Number = 20;
     worksheet.Range["D20"].Number = 30;
     worksheet.Range["D23"].Text = "Total";
     
     //Apply number format
     worksheet.Range["D16:E22"].NumberFormat = "$0.00";
     worksheet.Range["E23"].NumberFormat = "$0.00";
     
     //Apply incremental formula for column Amount by multiplying Qty and UnitPrice
     application.EnableIncrementalFormula = true;
     worksheet.Range["E16:E20"].Formula = "=C16*D16";
     
     //Formula for Sum the total
     worksheet.Range["E23"].Formula = "=SUM(E16:E22)";
     
     //Apply borders
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Black;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Black;
     
     //Apply font setting for cells with product details
     worksheet.Range["A3:E23"].CellStyle.Font.FontName = "Arial";
     worksheet.Range["A3:E23"].CellStyle.Font.Size = 10;
     worksheet.Range["A15:E15"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["A15:E15"].CellStyle.Font.Bold = true;
     worksheet.Range["D23:E23"].CellStyle.Font.Bold = true;
     
     //Apply cell color
     worksheet.Range["A15:E15"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply alignment to cells with product details
     worksheet.Range["A15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["C15:C22"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D15:E15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     
     //Apply row height and column width to look good
     worksheet.Range["A1"].ColumnWidth = 36;
     worksheet.Range["B1"].ColumnWidth = 11;
     worksheet.Range["C1"].ColumnWidth = 8;
     worksheet.Range["D1:E1"].ColumnWidth = 18;
     worksheet.Range["A1"].RowHeight = 47;
     worksheet.Range["A2"].RowHeight = 15;
     worksheet.Range["A3:A4"].RowHeight = 15;
     worksheet.Range["A5"].RowHeight = 18;
     worksheet.Range["A6"].RowHeight = 29;
     worksheet.Range["A7"].RowHeight = 18;
     worksheet.Range["A8"].RowHeight = 15;
     worksheet.Range["A9:A14"].RowHeight = 15;
     worksheet.Range["A15:A23"].RowHeight = 18;
     
     //Save the document as a stream and retrun the stream.
     using (MemoryStream stream = new MemoryStream())
     {
       //Save the created Excel document to MemoryStream
       workbook.SaveAs(stream);
       return stream;
     }
   }

Step 10: Create a new class file in the project, with name as FileUtils and add the following code to invoke the JavaScript action for downloading the file in browser.

C#
public static class FileUtils
   {
       public static ValueTask<object> SaveAs(this IJSRuntime js, string filename, byte[] data)
           => js.InvokeAsync<object>(
              "saveAsFile",
              filename,
              Convert.ToBase64String(data));
   }

Step 11: Add the following JavaScript function in the _Host.cshtml file present under Pages folder.

C#
<script type="text/javascript">
     function saveAsFile(filename, bytesBase64) {
   
     if (navigator.msSaveBlob) 
     {
       //Download document in Edge browser
       var data = window.atob(bytesBase64);
       var bytes = new Uint8Array(data.length);
       for (var i = 0; i < data.length; i++) 
       {
         bytes[i] = data.charCodeAt(i);
       }
       var blob = new Blob([bytes.buffer], { type: "application/octet-stream" });
       navigator.msSaveBlob(blob, filename);
     }
     else 
     {
       var link = document.createElement('a');
       link.download = filename;
       link.href = "data:application/octet-stream;base64," + bytesBase64;
       document.body.appendChild(link); // Needed for Firefox
       link.click();
       document.body.removeChild(link);
     }
   }
   </script>

Step 12: Add the following code under NavMenu.razor file present under Shared folder.

C#
<li class="nav-item px-3">
  <NavLink class="nav-link" href="Excel">
    <span class="oi oi-list-rich" aria-hidden="true"></span> Create Excel
  </NavLink>
</li>

Step 13: Add the service to services collection in ConfigureServices method of Startup.cs file.

C#
services.AddSingleton<ExcelService>();

A complete working example of how to create an Excel file in Blazor Server-Side application in C# is present on this GitHub page.

By executing the program, you will get the Excel file as below.
Output File

Read and Edit Excel file in Blazor Server-Side application

The below code snippet illustrates how to read and edit an Excel file in Blazor Server-Side application.

C#
//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
  //Instantiate the Excel application object
  IApplication application = excelEngine.Excel;
  
  //Set the default application version
  application.DefaultVersion = ExcelVersion.Xlsx;
  
  //Load the existing Excel workbook into IWorkbook
  FileStream inputStream = new FileStream("Sample.xlsx", FileMode.Open);
  IWorkbook workbook = application.Workbooks.Open(inputStream);
  
  //Get the first worksheet in the workbook into IWorksheet
  IWorksheet worksheet = workbook.Worksheets[0];
  
  //Assign some text in a cell
  worksheet.Range["A3"].Text = "Hello World";
  
  //Access a cell value from Excel
  var value = worksheet.Range["A1"].Value;
  
  //Save the document as a stream and retrun the stream.
  using (MemoryStream stream = new MemoryStream())
  {
    //Save the created Excel document to MemoryStream.
    workbook.SaveAs(stream);
  
    return stream;
  }
}

A complete working example of how to read and edit an Excel file in Blazor Server-Side application in C# is present on this GitHub page.

Create a simple Excel report in Blazor Client-Side application

The below steps illustrates the creation of a simple Invoice formatted Excel document in Blazor Client-Side application.

Step 1: Create a new C# Blazor Client-Side application project. Select Blazor App from the template and click the Next button.

Create Blazor Client Side application in Visual Studio

Step 2: Now, the project configuration window will popup. Click Create button to create a new project with the required project name.

Create Blazor Client Side application in Visual Studio

Step 3: Choose Blazor WebAssembly App and click Create button to create a new Blazor Client-Side application for .NET Core 3.0.0-preview9.

Create Blazor Client Side application in Visual Studio

Step 4: Install the Syncfusion.XlsIO.Net.Core NuGet package as reference to your Blazor application from NuGet.org.

Install Syncfusion.XlsIO.Net.Core Nuget Package

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components.

Step 5: Create a razor file with name as Excel under Pages folder and add the following namespaces in the file.

C#
@page "/Excel"
   @using Syncfusion.XlsIO;
   @using Syncfusion.Drawing;
   @using System.IO;
   @inject Microsoft.JSInterop.IJSRuntime JS

Step 6: Add the following code to create a new button.

CSHTML
<h2>Syncfusion Excel library (Essential XlsIO)</h2>
   <p>Syncfusion Excel library (Essential XlsIO)  is a Blazor Excel library used to create, read, edit, and convert Excel files in your applications without Microsoft Office dependencies.</p>
   <button class="btn btn-primary" @onclick="@CreateDocument">Create Document</button>

Step 7: Create a new async method with name as CreateDocument and include the following code snippet to create a simple Invoice formatted Excel document in Blazor Client-Side application.

C#
//Create an instance of ExcelEngine
   using (ExcelEngine excelEngine = new ExcelEngine())
   {
     IApplication application = excelEngine.Excel;
     application.DefaultVersion = ExcelVersion.Xlsx;
     
     //Create a workbook
     IWorkbook workbook = application.Workbooks.Create(1);
     IWorksheet worksheet = workbook.Worksheets[0];
     
     //Disable gridlines in the worksheet
     worksheet.IsGridLinesVisible = false;
     
     //Enter values to the cells from A3 to A5
     worksheet.Range["A3"].Text = "46036 Michigan Ave";
     worksheet.Range["A4"].Text = "Canton, USA";
     worksheet.Range["A5"].Text = "Phone: +1 231-231-2310";
     
     //Make the text bold
     worksheet.Range["A3:A5"].CellStyle.Font.Bold = true;
     
     //Merge cells
     worksheet.Range["D1:E1"].Merge();
     
     //Enter text to the cell B1 and apply formatting
     worksheet.Range["B1"].Text = "INVOICE";
     worksheet.Range["B1"].CellStyle.Font.Bold = true;
     worksheet.Range["B1"].CellStyle.Font.RGBColor = Color.FromArgb(42, 118, 189);
     worksheet.Range["B1"].CellStyle.Font.Size = 35;
     
     //Apply alignment in the cell B1
     worksheet.Range["B1"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["B1"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter values to the cells from D5 to E8
     worksheet.Range["D5"].Text = "INVOICE#";
     worksheet.Range["E5"].Text = "DATE";
     worksheet.Range["D6"].Number = 1028;
     worksheet.Range["E6"].Value = "12/31/2018";
     worksheet.Range["D7"].Text = "CUSTOMER ID";
     worksheet.Range["E7"].Text = "TERMS";
     worksheet.Range["D8"].Number = 564;
     worksheet.Range["E8"].Text = "Due Upon Receipt";
     
     //Apply RGB backcolor to the cells from D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["D7:E7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply known colors to the text in cells D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["D7:E7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Make the text as bold from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.Font.Bold = true;
     
     //Apply alignment to the cells from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D5:E5"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D7:E7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D6:E6"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter value and applying formatting in the cell A7
     worksheet.Range["A7"].Text = "  BILL TO";
     worksheet.Range["A7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["A7"].CellStyle.Font.Bold = true;
     worksheet.Range["A7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Apply alignment
     worksheet.Range["A7"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["A7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     
     //Enter values in the cells A8 to A12
     worksheet.Range["A8"].Text = "Steyn";
     worksheet.Range["A9"].Text = "Great Lakes Food Market";
     worksheet.Range["A10"].Text = "20 Whitehall Rd";
     worksheet.Range["A11"].Text = "North Muskegon,USA";
     worksheet.Range["A12"].Text = "+1 231-654-0000";
     
     //Create a Hyperlink for e-mail in the cell A13
     IHyperLink hyperlink = worksheet.HyperLinks.Add(worksheet.Range["A13"]);
     hyperlink.Type = ExcelHyperLinkType.Url;
     hyperlink.Address = "Steyn@greatlakes.com";
     hyperlink.ScreenTip = "Send Mail";
     
     //Merge column A and B from row 15 to 22
     worksheet.Range["A15:B15"].Merge();
     worksheet.Range["A16:B16"].Merge();
     worksheet.Range["A17:B17"].Merge();
     worksheet.Range["A18:B18"].Merge();
     worksheet.Range["A19:B19"].Merge();
     worksheet.Range["A20:B20"].Merge();
     worksheet.Range["A21:B21"].Merge();
     worksheet.Range["A22:B22"].Merge();
     
     //Enter details of products and prices
     worksheet.Range["A15"].Text = "  DESCRIPTION";
     worksheet.Range["C15"].Text = "QTY";
     worksheet.Range["D15"].Text = "UNIT PRICE";
     worksheet.Range["E15"].Text = "AMOUNT";
     worksheet.Range["A16"].Text = "Cabrales Cheese";
     worksheet.Range["A17"].Text = "Chocos";
     worksheet.Range["A18"].Text = "Pasta";
     worksheet.Range["A19"].Text = "Cereals";
     worksheet.Range["A20"].Text = "Ice Cream";
     worksheet.Range["C16"].Number = 3;
     worksheet.Range["C17"].Number = 2;
     worksheet.Range["C18"].Number = 1;
     worksheet.Range["C19"].Number = 4;
     worksheet.Range["C20"].Number = 3;
     worksheet.Range["D16"].Number = 21;
     worksheet.Range["D17"].Number = 54;
     worksheet.Range["D18"].Number = 10;
     worksheet.Range["D19"].Number = 20;
     worksheet.Range["D20"].Number = 30;
     worksheet.Range["D23"].Text = "Total";
     
     //Apply number format
     worksheet.Range["D16:E22"].NumberFormat = "$0.00";
     worksheet.Range["E23"].NumberFormat = "$0.00";
     
     //Apply incremental formula for column Amount by multiplying Qty and UnitPrice
     application.EnableIncrementalFormula = true;
     worksheet.Range["E16:E20"].Formula = "=C16*D16";
     
     //Formula for Sum the total
     worksheet.Range["E23"].Formula = "=SUM(E16:E22)";
     
     //Apply borders
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Black;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Black;
     
     //Apply font setting for cells with product details
     worksheet.Range["A3:E23"].CellStyle.Font.FontName = "Arial";
     worksheet.Range["A3:E23"].CellStyle.Font.Size = 10;
     worksheet.Range["A15:E15"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["A15:E15"].CellStyle.Font.Bold = true;
     worksheet.Range["D23:E23"].CellStyle.Font.Bold = true;
     
     //Apply cell color
     worksheet.Range["A15:E15"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply alignment to cells with product details
     worksheet.Range["A15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["C15:C22"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D15:E15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     
     //Apply row height and column width to look good
     worksheet.Range["A1"].ColumnWidth = 36;
     worksheet.Range["B1"].ColumnWidth = 11;
     worksheet.Range["C1"].ColumnWidth = 8;
     worksheet.Range["D1:E1"].ColumnWidth = 18;
     worksheet.Range["A1"].RowHeight = 47;
     worksheet.Range["A2"].RowHeight = 15;
     worksheet.Range["A3:A4"].RowHeight = 15;
     worksheet.Range["A5"].RowHeight = 18;
     worksheet.Range["A6"].RowHeight = 29;
     worksheet.Range["A7"].RowHeight = 18;
     worksheet.Range["A8"].RowHeight = 15;
     worksheet.Range["A9:A14"].RowHeight = 15;
     worksheet.Range["A15:A23"].RowHeight = 18;
     
     //Save the document as a stream and retrun the stream.
     using (MemoryStream stream = new MemoryStream())
     {
       //Save the created Excel document to MemoryStream
       workbook.SaveAs(stream);
       
       //Download the excel file
       await JS.SaveAs("Sample.xlsx", stream.ToArray());
     }
   }

Step 8: Create a class file with name as FileUtils and add the following code to invoke the JavaScript action for downloading the file in browser.

C#
public static class FileUtils
   {
       public static ValueTask<object> SaveAs(this IJSRuntime js, string filename, byte[] data)
           => js.InvokeAsync<object>(
              "saveAsFile",
              filename,
              Convert.ToBase64String(data));
   }

Step 9: Add the following JavaScript function in the index.html file present under wwwroot.

C#
<script type="text/javascript">
     function saveAsFile(filename, bytesBase64) {
   
     if (navigator.msSaveBlob) 
     {
       //Download document in Edge browser
       var data = window.atob(bytesBase64);
       var bytes = new Uint8Array(data.length);
       for (var i = 0; i < data.length; i++) 
       {
         bytes[i] = data.charCodeAt(i);
       }
       var blob = new Blob([bytes.buffer], { type: "application/octet-stream" });
       navigator.msSaveBlob(blob, filename);
     }
     else 
     {
       var link = document.createElement('a');
       link.download = filename;
       link.href = "data:application/octet-stream;base64," + bytesBase64;
       document.body.appendChild(link); // Needed for Firefox
       link.click();
       document.body.removeChild(link);
     }
   }
   </script>

Step 10: Add the following code under NavMenu.razor file present under Shared folder.

C#
<li class="nav-item px-3">
  <NavLink class="nav-link" href="Excel">
    <span class="oi oi-list-rich" aria-hidden="true"></span> Create Excel
  </NavLink>
</li>

A complete working example of how to create an Excel file in Blazor Client-Side Application in C# is present on this GitHub page.

By executing the program, you will get the Excel file as below.
Output File

Read and Edit Excel file in Blazor Client-Side application

The below code snippet illustrates how to read and edit an Excel file in Blazor Client-Side application.

C#
//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
  //Instantiate the Excel application object
  IApplication application = excelEngine.Excel;

  //Set the default application version
  application.DefaultVersion = ExcelVersion.Xlsx;

  //Load the existing Excel workbook into IWorkbook
  Stream inputStream = await client.GetStreamAsync("sample-data/Sample.xlsx");
  IWorkbook workbook = application.Workbooks.Open(inputStream);

  //Get the first worksheet in the workbook into IWorksheet
  IWorksheet worksheet = workbook.Worksheets[0];

  //Assign some text in a cell
  worksheet.Range["A3"].Text = "Hello World";

  //Access a cell value from Excel
  var value = worksheet.Range["A1"].Value;

  //Save the document as a stream and retrun the stream.
  using (MemoryStream stream = new MemoryStream())
  {
    //Save the created Excel document to MemoryStream
    workbook.SaveAs(stream);

    //Download the excel file
    await JS.SaveAs("Output.xlsx", stream.ToArray());
  }
}

A complete working example of how to read and edit an Excel file in Blazor Client-Side application in C# is present on this GitHub page.

NOTE

It is recommended to use Blazor Server-Side application to reduce the pay back load which is high in Blazor Client-Side.

Click here to explore the rich set of Syncfusion Excel library (Excel) features.

An online sample link to create an Excel document in Blazor.

Convert Excel to Image in Blazor Client-Side application

Create a new C# Blazor Client-Side project with target framework as .NET 8.0 by referring link
Install the SkiaSharp.Views.Blazor along with Syncfusion.XlsIORenderer.Net.Core from nuget.org.
Add below tag in your Blazor WASM csproj file.

CSHTML
<ItemGroup>
<NativeFileReference Include="$(SkiaSharpStaticLibraryPath)\2.0.23\*.a" />
</ItemGroup>

NOTE

Install wasm-tools and wasm-tools-net6 using dotnet workload install wasm-tools and dotnet workload install wasm-tools-net6 commands respectively, while facing issues related to skiasharp, during runtime.

Enable the below properties in csproj file.

CSHTML
<WasmNativeStrip>true</WasmNativeStrip>
<RunAOTCompilation>true</RunAOTCompilation>

Add the below code snippet in button click.

C#
//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
  IApplication application = excelEngine.Excel;
  application.DefaultVersion = ExcelVersion.Xlsx;

  //Load the Excel document
  Stream fileStream = await client.GetStreamAsync("sample-data/InputTemplate.xlsx");
  IWorkbook workbook = application.Workbooks.Open(fileStream);
  IWorksheet worksheet = workbook.Worksheets[0];

  //Initialize XlsIORenderer
  application.XlsIORenderer = new XlsIORenderer();

  //Initialize MemoryStream
  using (MemoryStream stream = new MemoryStream())
  {
    //Convert worksheet to image
    worksheet.ConvertToImage(worksheet.UsedRange, stream);

    //Download the png file
    await JS.SaveAs("ExcelToImage.png", stream.ToArray());
  }
}

A complete working example of how to convert an Excel worksheet to image in Blazor Client-Side application in C# is present on this GitHub page.

Convert Excel to PDF in Blazor Client-Side application

Create a new C# Blazor Client-Side project with target framework as .NET 8.0 by referring link
Install the SkiaSharp.Views.Blazor along with Syncfusion.XlsIORenderer.Net.Core from nuget.org.
Add below tag in your Blazor WASM csproj file.

CSHTML
<ItemGroup>
<NativeFileReference Include="$(SkiaSharpStaticLibraryPath)\2.0.23\*.a" />
</ItemGroup>

NOTE

Install wasm-tools and wasm-tools-net6 using dotnet workload install wasm-tools and dotnet workload install wasm-tools-net6 commands respectively, while facing issues related to skiasharp, during runtime.

Enable the below properties in csproj file.

CSHTML
<WasmNativeStrip>true</WasmNativeStrip>
<RunAOTCompilation>true</RunAOTCompilation>

Add the below code snippet in button click.

C#
//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
  IApplication application = excelEngine.Excel;
  application.DefaultVersion = ExcelVersion.Xlsx;

  //Load the Excel document
  Stream fileStream = await client.GetStreamAsync("sample-data/InputTemplate.xlsx");
  IWorkbook workbook = application.Workbooks.Open(fileStream);

  //Initialize XlsIORenderer
  XlsIORenderer renderer = new XlsIORenderer();

  //Convert Excel document into PDF document
  PdfDocument pdfDocument = renderer.ConvertToPDF(workbook);

  //Initialize MemoryStream
  using (MemoryStream stream = new MemoryStream())
  {
    //Save the created PDF document to MemoryStream
    pdfDocument.Save(stream);

    //Download the pdf file
    await JS.SaveAs("ExcelToPDF.pdf", stream.ToArray());
  }
}

A complete working example of how to convert an Excel file to PDF in Blazor Client-Side application in C# is present on this GitHub page.

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components. You can also explore our Blazor Excel library demo that shows how to create and modify Excel files from C# with just five lines of code.

Create a simple Excel report in Blazor Server-Side Web application

The below steps illustrates the creation of a simple Invoice formatted Excel document in Blazor Server-Side web application.

Step 1: Create a new C# Blazor Web application project.

Create Blazor Server Side web application in Visual Studio

Step 2: Name the project.

Name the Blazor Web Server Side application in Visual Studio

Step 3: Select the framework and click Create button.

Select the framework in Blazor Server Side application in Visual Studio

Step 4: Install the Syncfusion.XlsIO.Net.Core NuGet package as reference to your Blazor web application from NuGet.org.

Install Syncfusion.XlsIO.Net.Core Nuget Package

NOTE

Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, you also have to add “Syncfusion.Licensing” assembly reference and include a license key in your projects. Please refer to this link to know about registering Syncfusion license key in your applications to use our components.

Step 5: Create a razor file with name as Excel under Pages folder, which is located inside the Components folder and include the following namespaces in the file.

C#
@rendermode InteractiveServer
   @page "/excel"
   @using System.IO;
   @using Create_Excel;
   @inject Create_Excel.Components.Data.ExcelService service
   @inject Microsoft.JSInterop.IJSRuntime JS

Step 6: Add the following code to create a new button.

CSHTML
<h2>Syncfusion Excel library (Essential XlsIO)</h2>
   <p>Syncfusion Excel library (Essential XlsIO)  is a Blazor Excel library used to create, read, edit, and convert Excel files in your applications without Microsoft Office dependencies.</p>
   <button class="btn btn-primary" @onclick="@CreateDocument">Create Document</button>

Step 7: Add the following code in Excel.razor file to create and download the Excel document.

C#
@code {
       MemoryStream excelStream;
   
       /// <summary>
       /// Create and download the Excel document
       /// </summary>
       protected async void CreateDocument()
       {
           excelStream = service.CreateExcel();
           await JS.SaveAs("Sample.xlsx", excelStream.ToArray());
       }
   }

Step 8: Create a new cs file with name as ExcelService under Data folder and include the following namespaces in the file.

C#
using Syncfusion.XlsIO;
   using Syncfusion.Drawing;
   using System.IO;

Step 9: Create a new MemoryStream method with name as CreateExcel and include the following code snippet to create a simple Invoice formatted Excel document in Blazor Server-Side web application.

C#
//Create an instance of ExcelEngine
   using (ExcelEngine excelEngine = new ExcelEngine())
   {
     IApplication application = excelEngine.Excel;
     application.DefaultVersion = ExcelVersion.Xlsx;
     
     //Create a workbook
     IWorkbook workbook = application.Workbooks.Create(1);
     IWorksheet worksheet = workbook.Worksheets[0];
     
     //Add a picture
     FileStream imageStream = new FileStream("AdventureCycle.png", FileMode.Open);
     Image image = Image.FromStream(imageStream);
     IPictureShape shape = worksheet.Pictures.AddPicture(1, 1, image, 20, 20);
     
     //Disable gridlines in the worksheet
     worksheet.IsGridLinesVisible = false;
     
     //Enter values to the cells from A3 to A5
     worksheet.Range["A3"].Text = "46036 Michigan Ave";
     worksheet.Range["A4"].Text = "Canton, USA";
     worksheet.Range["A5"].Text = "Phone: +1 231-231-2310";
     
     //Make the text bold
     worksheet.Range["A3:A5"].CellStyle.Font.Bold = true;
     
     //Merge cells
     worksheet.Range["D1:E1"].Merge();
     
     //Enter text to the cell D1 and apply formatting
     worksheet.Range["D1"].Text = "INVOICE";
     worksheet.Range["D1"].CellStyle.Font.Bold = true;
     worksheet.Range["D1"].CellStyle.Font.RGBColor = Color.FromArgb(42, 118, 189);
     worksheet.Range["D1"].CellStyle.Font.Size = 35;
     
     //Apply alignment in the cell D1
     worksheet.Range["D1"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignRight;
     worksheet.Range["D1"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter values to the cells from D5 to E8
     worksheet.Range["D5"].Text = "INVOICE#";
     worksheet.Range["E5"].Text = "DATE";
     worksheet.Range["D6"].Number = 1028;
     worksheet.Range["E6"].Value = "12/31/2018";
     worksheet.Range["D7"].Text = "CUSTOMER ID";
     worksheet.Range["E7"].Text = "TERMS";
     worksheet.Range["D8"].Number = 564;
     worksheet.Range["E8"].Text = "Due Upon Receipt";
     
     //Apply RGB backcolor to the cells from D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["D7:E7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply known colors to the text in cells D5 to E8
     worksheet.Range["D5:E5"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["D7:E7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Make the text as bold from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.Font.Bold = true;
     
     //Apply alignment to the cells from D5 to E8
     worksheet.Range["D5:E8"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D5:E5"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D7:E7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     worksheet.Range["D6:E6"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignTop;
     
     //Enter value and applying formatting in the cell A7
     worksheet.Range["A7"].Text = "  BILL TO";
     worksheet.Range["A7"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     worksheet.Range["A7"].CellStyle.Font.Bold = true;
     worksheet.Range["A7"].CellStyle.Font.Color = ExcelKnownColors.White;
     
     //Apply alignment
     worksheet.Range["A7"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["A7"].CellStyle.VerticalAlignment = ExcelVAlign.VAlignCenter;
     
     //Enter values in the cells A8 to A12
     worksheet.Range["A8"].Text = "Steyn";
     worksheet.Range["A9"].Text = "Great Lakes Food Market";
     worksheet.Range["A10"].Text = "20 Whitehall Rd";
     worksheet.Range["A11"].Text = "North Muskegon,USA";
     worksheet.Range["A12"].Text = "+1 231-654-0000";
     
     //Create a Hyperlink for e-mail in the cell A13
     IHyperLink hyperlink = worksheet.HyperLinks.Add(worksheet.Range["A13"]);
     hyperlink.Type = ExcelHyperLinkType.Url;
     hyperlink.Address = "Steyn@greatlakes.com";
     hyperlink.ScreenTip = "Send Mail";
     
     //Merge column A and B from row 15 to 22
     worksheet.Range["A15:B15"].Merge();
     worksheet.Range["A16:B16"].Merge();
     worksheet.Range["A17:B17"].Merge();
     worksheet.Range["A18:B18"].Merge();
     worksheet.Range["A19:B19"].Merge();
     worksheet.Range["A20:B20"].Merge();
     worksheet.Range["A21:B21"].Merge();
     worksheet.Range["A22:B22"].Merge();
     
     //Enter details of products and prices
     worksheet.Range["A15"].Text = "  DESCRIPTION";
     worksheet.Range["C15"].Text = "QTY";
     worksheet.Range["D15"].Text = "UNIT PRICE";
     worksheet.Range["E15"].Text = "AMOUNT";
     worksheet.Range["A16"].Text = "Cabrales Cheese";
     worksheet.Range["A17"].Text = "Chocos";
     worksheet.Range["A18"].Text = "Pasta";
     worksheet.Range["A19"].Text = "Cereals";
     worksheet.Range["A20"].Text = "Ice Cream";
     worksheet.Range["C16"].Number = 3;
     worksheet.Range["C17"].Number = 2;
     worksheet.Range["C18"].Number = 1;
     worksheet.Range["C19"].Number = 4;
     worksheet.Range["C20"].Number = 3;
     worksheet.Range["D16"].Number = 21;
     worksheet.Range["D17"].Number = 54;
     worksheet.Range["D18"].Number = 10;
     worksheet.Range["D19"].Number = 20;
     worksheet.Range["D20"].Number = 30;
     worksheet.Range["D23"].Text = "Total";
     
     //Apply number format
     worksheet.Range["D16:E22"].NumberFormat = "$0.00";
     worksheet.Range["E23"].NumberFormat = "$0.00";
     
     //Apply incremental formula for column Amount by multiplying Qty and UnitPrice
     application.EnableIncrementalFormula = true;
     worksheet.Range["E16:E20"].Formula = "=C16*D16";
     
     //Formula for Sum the total
     worksheet.Range["E23"].Formula = "=SUM(E16:E22)";
     
     //Apply borders
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A16:E22"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Grey_25_percent;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].LineStyle = ExcelLineStyle.Thin;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeTop].Color = ExcelKnownColors.Black;
     worksheet.Range["A23:E23"].CellStyle.Borders[ExcelBordersIndex.EdgeBottom].Color = ExcelKnownColors.Black;
     
     //Apply font setting for cells with product details
     worksheet.Range["A3:E23"].CellStyle.Font.FontName = "Arial";
     worksheet.Range["A3:E23"].CellStyle.Font.Size = 10;
     worksheet.Range["A15:E15"].CellStyle.Font.Color = ExcelKnownColors.White;
     worksheet.Range["A15:E15"].CellStyle.Font.Bold = true;
     worksheet.Range["D23:E23"].CellStyle.Font.Bold = true;
     
     //Apply cell color
     worksheet.Range["A15:E15"].CellStyle.Color = Color.FromArgb(42, 118, 189);
     
     //Apply alignment to cells with product details
     worksheet.Range["A15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignLeft;
     worksheet.Range["C15:C22"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     worksheet.Range["D15:E15"].CellStyle.HorizontalAlignment = ExcelHAlign.HAlignCenter;
     
     //Apply row height and column width to look good
     worksheet.Range["A1"].ColumnWidth = 36;
     worksheet.Range["B1"].ColumnWidth = 11;
     worksheet.Range["C1"].ColumnWidth = 8;
     worksheet.Range["D1:E1"].ColumnWidth = 18;
     worksheet.Range["A1"].RowHeight = 47;
     worksheet.Range["A2"].RowHeight = 15;
     worksheet.Range["A3:A4"].RowHeight = 15;
     worksheet.Range["A5"].RowHeight = 18;
     worksheet.Range["A6"].RowHeight = 29;
     worksheet.Range["A7"].RowHeight = 18;
     worksheet.Range["A8"].RowHeight = 15;
     worksheet.Range["A9:A14"].RowHeight = 15;
     worksheet.Range["A15:A23"].RowHeight = 18;
     
     //Save the document as a stream and retrun the stream.
     using (MemoryStream stream = new MemoryStream())
     {
       //Save the created Excel document to MemoryStream
       workbook.SaveAs(stream);
       return stream;
     }
   }

Step 10: Create a new class file in the project, with name as FileUtils and add the following code to invoke the JavaScript action for downloading the file in browser.

C#
public static class FileUtils
   {
       public static ValueTask<object> SaveAs(this IJSRuntime js, string filename, byte[] data)
           => js.InvokeAsync<object>(
              "saveAsFile",
              filename,
              Convert.ToBase64String(data));
   }

Step 11: Add the following JavaScript function in the App.razor.

C#
<script type="text/javascript">
     function saveAsFile(filename, bytesBase64) {
   
     if (navigator.msSaveBlob) 
     {
       //Download document in Edge browser
       var data = window.atob(bytesBase64);
       var bytes = new Uint8Array(data.length);
       for (var i = 0; i < data.length; i++) 
       {
         bytes[i] = data.charCodeAt(i);
       }
       var blob = new Blob([bytes.buffer], { type: "application/octet-stream" });
       navigator.msSaveBlob(blob, filename);
     }
     else 
     {
       var link = document.createElement('a');
       link.download = filename;
       link.href = "data:application/octet-stream;base64," + bytesBase64;
       document.body.appendChild(link); // Needed for Firefox
       link.click();
       document.body.removeChild(link);
     }
   }
   </script>

Step 12: Add the following code in NavMenu.razor file present under Layout folder.

C#
<div class="nav-item px-3">
    <NavLink class="nav-link" href="Excel">
        <span class="oi oi-list-rich" aria-hidden="true"></span> Create Excel
    </NavLink>
</div>

Step 13: Add the service in the Program.cs file.

C#
builder.Services.AddScoped <Create_Excel.Components.Data.ExcelService>();

A complete working example of how to create an Excel file in Blazor Server-Side web application in C# is present on this GitHub page.

By executing the program, you will get the Excel file as below.
Output File

Read and Edit Excel file in Blazor Server-Side web application

The below code snippet illustrates how to read and edit an Excel file in Blazor Server-Side web application.

C#
//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
{
  //Instantiate the Excel application object
  IApplication application = excelEngine.Excel;
  
  //Set the default application version
  application.DefaultVersion = ExcelVersion.Xlsx;
  
  //Load the existing Excel workbook into IWorkbook
  FileStream inputStream = new FileStream("Sample.xlsx", FileMode.Open);
  IWorkbook workbook = application.Workbooks.Open(inputStream);
  
  //Get the first worksheet in the workbook into IWorksheet
  IWorksheet worksheet = workbook.Worksheets[0];
  
  //Assign some text in a cell
  worksheet.Range["A3"].Text = "Hello World";
  
  //Access a cell value from Excel
  var value = worksheet.Range["A1"].Value;
  
  //Save the document as a stream and retrun the stream.
  using (MemoryStream stream = new MemoryStream())
  {
    //Save the created Excel document to MemoryStream.
    workbook.SaveAs(stream);
  
    return stream;
  }
}

A complete working example of how to read and edit an Excel file in Blazor Server-Side web application in C# is present on this GitHub page.