We use cookies to give you the best experience on our website. If you continue to browse, then you agree to our privacy policy and cookie policy. Image for the cookie policy date
Unfortunately, activation email could not send to your email. Please try again.
Syncfusion Feedback

Write to existing Excel in C#, VB.NET

Platform: WinForms |
Control: XlsIO

Syncfusion Excel (XlsIO) library is a .NET Excel library used to create, read, and edit Excel documents. Using this library, you can write data into an existing Excel worksheet in C# and VB.NET.

Steps to write data into an Excel file programmatically:

Step 1: Create a new C# console application project.

Create Console application in Visual Studio

Create a new C# console application

Step 2: Install Syncfusion.XlsIO.WinForms NuGet package as a reference to your .NET Framework applications from the NuGet.org.

Add XlsIO reference to the project

Install NuGet package

Step 3: Include the following namespaces in the Program.cs file.


using Syncfusion.XlsIO;
using System.IO;
using System.Reflection;



Imports Syncfusion.XlsIO
Imports System.IO
Imports System.Reflection


Step 4: Add the following code snippet to write data into an existing Excel file.


//Create an instance of ExcelEngine
using (ExcelEngine excelEngine = new ExcelEngine())
  //Set the default application version as Excel 2016
  excelEngine.Excel.DefaultVersion = ExcelVersion.Excel2016;
  //Open existing workbook with data entered
  Assembly assembly = typeof(Program).GetTypeInfo().Assembly;
  Stream fileStream = assembly.GetManifestResourceStream("WriteData.Sample.xlsx");
  IWorkbook workbook = application.Workbooks.Open(fileStream);
  //Access first worksheet from the workbook instance
  IWorksheet worksheet = workbook.Worksheets[0];
  //Insert sample text into cell “A1”
  worksheet.Range["A1"].Text = "Syncfusion Essential XlsIO";
  //Save the workbook to disk in xlsx format



'Create an instance of ExcelEngine
Using excelEngine As ExcelEngine = New ExcelEngine
  'Set the default application version as Excel 2016
  excelEngine.Excel.DefaultVersion = ExcelVersion.Excel2016
  'Open an existing workbook with data entered
  Dim assembly As Assembly = GetType(Program).GetTypeInfo.Assembly
  Dim fileStream As Stream = assembly.GetManifestResourceStream("WriteData.Sample.xlsx")
  Dim workbook As IWorkbook = application.Workbooks.Open(fileStream)
  'Access first worksheet from the workbook instance
  Dim worksheet As IWorksheet = workbook.Worksheets(0)
  'Insert sample text into cell “A1”
  worksheet.Range("A1").Text = "Syncfusion Essential XlsIO"
  'Save the workbook to disk in xlsx format
End Using


A complete working example to write data to an existing Excel file along with input file used can be downloaded from Write Data to Existing Excel file.zip

By executing the program, you will get the output Excel file as shown below.

Write Data to Existing Excel File

Output Excel document

Take a moment to peruse the documentation, where you can find basic worksheet data manipulation options along with features like Conditional Formatting, worksheet calculations through Formulas, adding Charts in worksheet or workbook, organizing and analyzing data through Tables and Pivot Tables, appending multiple records to worksheet using Template Markers, and most importantly PDF and Image conversions with code examples.

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

An online sample link to generate Excel file.

See Also:

Read Excel from Code in C#, VB.NET


Starting with v16.2.0.x, if you reference Syncfusion assemblies from trial setup or from the NuGet feed, include a license key in your projects. Refer the link to learn about generating and registering Syncfusion license key in your application to use the components without trail message.


2X faster development

The ultimate WinForms UI toolkit to boost your development speed.
You must log in to leave a comment

Please sign in to access our KB

This page will automatically be redirected to the sign-in page in 10 seconds.

Up arrow icon

Warning Icon You are using an outdated version of Internet Explorer that may not display all features of this and other websites. Upgrade to Internet Explorer 8 or newer for a better experience.Close Icon

Live Chat Icon For mobile