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Posted 5 Dec 2013


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A free "Export to Excel" C# class, using OpenXML

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17 Dec 2013CPOL4 min read
How to easily add an "export to Excel" feature to your app


It's amazing that even now, in 2013, there are so many developers still asking for help on how to write C# and VB.NET code to export their data to Excel.

Even worse, a lot of them will stumble on articles suggesting that they should write their data to a comma-separated file, but to give the file a .xls extension.

So today, I'm going to walkthrough how to use my C# "Export to Excel" class which you can add to your C# WinForms / WPF / ASP.NET application, using one line of code.

Depending on whether your data is stored in a DataSet, DataTable, or List<>, you simply need to call one of these three functions, and tell them what (Excel) file name you want to write to.

public static bool CreateExcelDocument<T>(List<T> list, string ExcelFilename
public static bool CreateExcelDocument(DataTable dt, string ExcelFilename
public static bool CreateExcelDocument(DataSet ds, string ExcelFilename)

Here's a simple example.

We create a DataSet, fill it with some data (just add your own CreateSampleData function), then call the CreateExcelFile.CreateExcelDocument function, passing it the DataSet and a filename:

// Step 1: Create a DataSet, and put some sample data in it
DataSet ds = CreateSampleData();

// Step 2: Create the Excel .xlsx file
    CreateExcelFile.CreateExcelDocument(ds, "C:\\Sample.xlsx");
catch (Exception ex)
    MessageBox.Show("Couldn't create Excel file.\r\nException: " + ex.Message);

And that's all you have to do. The CreateExcelDocument function will create a "real" Excel file for you.

For example, if you had a created a DataSet containing three DataTables called:

  • Drivers
  • Vehicles,
  • Vehicle Owners,

..then here's what your Excel file would look like. The class would create one worksheet per DataTable, and each worksheet would contain the data from that DataTable.

Sample spreadsheet

The full source code for this C# class is freely downloadable here (click on the "Browse code" link in the left-hand panel), or you can download this full demo, plus a VB.NET version of the class, from my blog, MikesKnowledgeBase.

Adding the library to your application

The C# code above shows how easy it is to call the CreateExcelFile class.

DataSet ds = CreateSampleData();
CreateExcelFile.CreateExcelDocument(ds, "C:\\Sample.xlsx");

However, to use this library, you'll need to add two files from the free Microsoft OpenXML SDK:

  • DocumentFormat.OpenXml.dll: From the free Microsoft Open XML SDK library
  • WindowsBase.dll: From the Microsoft .NET Framework library

Add these two DLLs to your project's References section, and remember to set them to "Copy Local".

Copy Local

Then, just download the CreateExcelFile.cs file (via the "Browse code" link in CodeProject's left-hand panel), and add it to your application. 

And that's it.

Regardless of if your data is stored in a List<>, DataTable, or DataSet, you can export it to a "real" Office 2007 Excel .xlsx file using that one line of code.

And because it is created using the OpenXML library, you can run this code on machines which don't have Excel installed.


For ASP.NET developers, I've added three extra functions.

public static bool CreateExcelDocument<T>(List<T> list, string filename, System.Web.HttpResponse Response)
public static bool CreateExcelDocument(DataTable dt, string filename, System.Web.HttpResponse Response)
public static bool CreateExcelDocument(DataSet ds, string filename, System.Web.HttpResponse Response)

Rather than creating the Excel file in a temporary directory, then having to load in the file and output it to the webpage's HttpResponse, you can get the library to write directly to the HttpResponse.

However, by default, this functionality is disabled (to prevent build issues for the non ASP.NET developers). To enable these three functions, you need to make two changes.

First, uncomment the top line of the CreateExcelFile.cs code, so that it now reads:


Now, you need to add a Reference to the System.Web .NET library:

Adding a reference

Once you've done these two steps, the CreateExcelFile library is ready to go.

For example, in this example, my ASP.NET C# code has a list of Employee records, stored in a List<Employeee>. I add an "Export to Excel" button to my webpage, and when the user clicks on it, I just need one simple call to the CreateExcelFile class.

// In this example, I have a defined a List of my Employee objects.<br />class Employee;
List<Employee> listOfEmployees = new List<Employee>();
// The following ASP.Net code gets run when I click on my "Export to Excel" button.
protected void btnExportToExcel_Click(object sender, EventArgs e)
    // It doesn't get much easier than this...
    CreateExcelFile.CreateExcelDocument(listOfEmployees, "Employees.xlsx", Response);

And that's it. A real Excel file, in one line of code.

Going forward

You'll notice that this library is excellent for one job - writing plain, boring data to an Excel file. I haven't attempted to add any classes to add formatting, colors, pivot tables or anything else.

However, this class is an excellent way to get started (without paying for third-party software to create the Excel file for you), and if you want to take this further, you'll soon find that Googling will easily find you extra source code to add on top of this.

For example, if you wanted to add a background color to some of the cells in the Excel file, simply Google "open XML background color" and you'll have many articles showing you how to do this.

The reason I wrote this article is that I found that it was very hard to find a free, easy to use C# library which actually created the OpenXML Excel file in the first place.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Mike Gledhill
Software Developer
Switzerland Switzerland
Programming since the age of 15, with experience in C# and iPad software development.
Working as a software developer for a financial company in Zurich, Switzerland.

More developer tips'n'trip at my website:

Comments and Discussions

QuestionFix Column Width as per highest string data into the cell Pin
Sopan Maiti2-Jun-15 4:42
MemberSopan Maiti2-Jun-15 4:42 
GeneralCodeProject issue Pin
Michael Gledhill1-Jun-15 22:17
MemberMichael Gledhill1-Jun-15 22:17 
GeneralRe: CodeProject issue Pin
Member 115248382-Aug-15 10:50
MemberMember 115248382-Aug-15 10:50 
GeneralRe: CodeProject issue Pin
reddyreddy720-Aug-15 9:02
Memberreddyreddy720-Aug-15 9:02 
Questioninsert into Pin
Member 871442125-May-15 10:10
MemberMember 871442125-May-15 10:10 
QuestionAwesome Pin
OmidGer6-May-15 5:26
MemberOmidGer6-May-15 5:26 
AnswerRe: Awesome Pin
Michael Gledhill7-May-15 22:07
MemberMichael Gledhill7-May-15 22:07 
QuestionHow to format a column as Date? Pin
Jaime Stuardo - Chile2-May-15 8:30
MemberJaime Stuardo - Chile2-May-15 8:30 
This class only take care a int and string cells, but how about date data type? Currently, date is formatted as string.

modified 2-May-15 13:39pm.

AnswerRe: How to format a column as Date? Pin
Michael Gledhill7-May-15 23:49
MemberMichael Gledhill7-May-15 23:49 
QuestionLanguage dependent column names Pin
Mårten Sörliden8-Apr-15 3:40
professionalMårten Sörliden8-Apr-15 3:40 
QuestionAddHeader needs filename='" + filename + "'" to work in Google Chrome Pin
Mårten Sörliden7-Apr-15 6:13
professionalMårten Sörliden7-Apr-15 6:13 
QuestionWhat about this DLL? Pin
dietmar paul schoder28-Feb-15 4:43
professionaldietmar paul schoder28-Feb-15 4:43 
AnswerRe: What about this DLL? Pin
Michael Gledhill18-Mar-15 2:30
MemberMichael Gledhill18-Mar-15 2:30 
GeneralRe: What about this DLL? Pin
dietmar schoder18-Mar-15 2:43
Memberdietmar schoder18-Mar-15 2:43 
QuestionIn Webmatrix I can't get it to work Pin
MarcelloCarrabba10-Feb-15 6:24
professionalMarcelloCarrabba10-Feb-15 6:24 
Questionxls extension error Pin
Member 1106205626-Jan-15 5:51
MemberMember 1106205626-Jan-15 5:51 
AnswerRe: xls extension error Pin
Mike Gledhill29-Jan-15 23:23
MemberMike Gledhill29-Jan-15 23:23 
QuestionError related to Hexadecimal characters Pin
magupta776-Jan-15 0:49
Membermagupta776-Jan-15 0:49 
AnswerRe: Error related to Hexadecimal characters Pin
Mike Gledhill29-Jan-15 23:24
MemberMike Gledhill29-Jan-15 23:24 
QuestionDoesn't work with List<string> Pin
Member 1010915510-Dec-14 6:26
MemberMember 1010915510-Dec-14 6:26 
AnswerRe: Doesn't work with List<string> Pin
alvin19886-May-15 13:23
Memberalvin19886-May-15 13:23 
QuestionExport to excel with image Pin
Member 112844648-Dec-14 20:27
MemberMember 112844648-Dec-14 20:27 
AnswerRe: Export to excel with image Pin
Mike Gledhill29-Jan-15 23:28
MemberMike Gledhill29-Jan-15 23:28 
QuestionAnother ataboy - and a quick question on DateTime values Pin
tlmrogers8-Dec-14 11:59
Membertlmrogers8-Dec-14 11:59 
AnswerRe: Another ataboy - and a quick question on DateTime values Pin
Michael Gledhill7-May-15 23:49
MemberMichael Gledhill7-May-15 23:49 

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