Microsoft Office Interop (Excel Automation) in C# and VB.NET

Microsoft Office Interop (Excel Automation) is an option when creating/reading Excel files (XLS, XLSX, CSV) from C# or VB.NET application, but it has many drawbacks.

Some issues when using Microsoft Office Interop (Excel Automation) from C# or VB.NET are:

  • It requires a license for Microsoft Office on every client machine.
  • It requires all client machines to have the same version of Microsoft Excel installed.
  • It works only on Windows operating systems.
  • When using Automation, Microsoft Excel is loaded in the background, using a lot of MB and loading a large number of files and DLLs.
  • Microsoft Office applications (including Excel) were designed as UI applications and, because of that, API is very slow. Generating a single worksheet with 200 rows and 200 columns takes 239.4 seconds on our test machine.
  • Microsoft doesn't recommend using Excel Automation (or any Office Interop) on the server, see Considerations for server-side Automation of Office.

We are proud that our Excel .NET library is one of the best alternatives for Microsoft Office Interop (Excel Automation).

Better than Excel Automation

The following table lists pros and cons of using the GemBox.Spreadsheet component over Microsoft Excel automation.

Microsoft Excel automation GemBox.Spreadsheet component
Requires a license for Microsoft Excel on every client machine. Requires only the developer using our component to have one GemBox.Spreadsheet developer license, even if the developed application will be installed on thousands of client machines.
Requires all client machines to have the same version of Microsoft Excel installed. Files generated with GemBox.Spreadsheet are compatible with all versions starting from Excel 97, OpenOffice, and LibreOffice, so any of these products can (but don't have to) be installed on a client machine.
Works only on Windows operating systems. With support for .NET Standard 2.0, GemBox.Spreadsheet works on Windows, Linux, Unix, and OSX operating systems (via .NET Core 2.0 that implements .NET Standard 2.0) and on Mono, Xamarin, and Universal Windows platforms (that implement .NET Standard 2.0).
When using automation, Excel is loaded in the background, using a lot of MB and loading a large number of files and DLLs. GemBox.Spreadsheet is a single component that uses only 5 MB. Additional memory is allocated only when needed to perform certain operations.
Microsoft Excel was designed as a UI application and, because of that, API is very slow. Generating a single worksheet with 200 rows and 200 columns takes 240 seconds on our test machine. GemBox.Spreadsheet is designed for processing large numbers of Excel files. The same test took 0.9 seconds on our test machine (266 times faster than Microsoft Excel).
Microsoft Excel API is exposed as a COM object. This results in the same disadvantages as with calling any COM object from the managed code (type conversions, need for COM wrapper, bad integration with .NET Framework, etc.). GemBox.Spreadsheet is a pure .NET component, designed and developed to conform to Microsoft standards for .NET libraries.

Outperforming competition

When comparing and evaluating different XLSX, XLS, ODS, CSV reading products and HTML, PDF and XPS reporting products, don't forget the following considerations:

Plain and fair licensing

We don't charge for additional server licenses. You can use our component for an unlimited number of projects (you don't need to purchase additional "OEM licenses") and we don't force you to purchase subscription packages.

Our licensing is very simple: every developer working with our component needs to have a developer license. We don't care if it is a Windows or web application, how many servers you use, or if you have just one customer or millions of customers.

Performance

In the case of a desktop application, you don't want your users to wait 20 seconds for every single report. In the case of a web application, you want your server to simultaneously support as many users as possible. Our test programs generate a single XLS file with 200 rows and 200 columns of tabular data. Half of the values are strings and half are numbers, with 50% of cells having some cell style applied (font size and border). These were the results on our test machine:

  • Microsoft Excel automation takes 240 seconds to generate the file.
  • GemBox.Spreadsheet takes 0.9 seconds to generate the file (266 times faster).

The performance example is included here, so you are free to do the test yourself and see how our component performs with the tabular data that you require.

Clean and easy to use API

GemBox.Spreadsheet is designed and developed to conform to Microsoft's standards for .NET libraries. Caching also enables you to access the worksheet in a more natural way. For example, changing cell text orientation would be one line in GemBox.Spreadsheet:

ws.Cells[6, 0].Style.Rotation = 30;

and three lines in one of the competing products:

  XLStyle someStyle = new XLStyle(book);
  someStyle.Rotation = 30;
  sheet[6, 0].Style = someStyle;

The latter is a hassle and forces you to think about Excel's unique cell style limit. In other words, you will have to pay attention to not create the same cell style again in a more complex worksheet.

Portability

GemBox.Spreadsheet works on Windows, Linux, Unix, and OSX operating systems (via .NET Core 2.0 that implements .NET Standard 2.0) and on Mono, Xamarin, and Universal Windows platforms (that implement .NET Standard 2.0).

100% managed code

Some similar products (and Microsoft Excel object) are old COM components with .NET RCW (Runtime Callable Wrapper). This brings many performance and interoperability disadvantages as every method call that you make goes through the wrapper until it reaches C++ code. On the other hand, our GemBox.Spreadsheet component is 100% managed, written entirely in C#, and designed to support both Visual Basic .NET and C# in an equal manner.

Test reading files with GemBox.Spreadsheet online

You can test reading the content of your Excel files with the interactive example below. Just upload your file and click on Run Example. After clicking on Run example, the C#/VB.NET code will be compiled, and the content of your file will be read with only .NET framework and the GemBox.Spreadsheet component.

The following example loads the Excel file, iterates through its cells, and appends the content of the cells to StringBuilder.

Upload your file (Drag file here)
using System;
using System.Text;
using GemBox.Spreadsheet;

class Program
{
    static void Main()
    {
        // If you are using the Professional version, enter your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");

        var workbook = ExcelFile.Load("%InputFileName%");

        var sb = new StringBuilder();

        // Iterate through all worksheets in an Excel workbook.
        foreach (var worksheet in workbook.Worksheets)
        {
            sb.AppendLine();
            sb.AppendFormat("{0} {1} {0}", new string('-', 25), worksheet.Name);

            // Iterate through all rows in an Excel worksheet.
            foreach (var row in worksheet.Rows)
            {
                sb.AppendLine();

                // Iterate through all allocated cells in an Excel row.
                foreach (var cell in row.AllocatedCells)
                    if (cell.ValueType != CellValueType.Null)
                        sb.Append(string.Format("{0} [{1}]", cell.Value, cell.ValueType).PadRight(25));
                    else
                        sb.Append(new string(' ', 25));
            }
        }

        Console.WriteLine(sb.ToString());
    }
}
Imports System
Imports System.Text
Imports GemBox.Spreadsheet

Module Program

    Sub Main()

        ' If you are using the Professional version, enter your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")

        Dim workbook = ExcelFile.Load("%InputFileName%")

        Dim sb = New StringBuilder()

        ' Iterate through all worksheets in an Excel workbook.
        For Each worksheet In workbook.Worksheets

            sb.AppendLine()
            sb.AppendFormat("{0} {1} {0}", New String("-"c, 25), worksheet.Name)

            ' Iterate through all rows in an Excel worksheet.
            For Each row In worksheet.Rows

                sb.AppendLine()

                ' Iterate through all allocated cells in an Excel row.
                For Each cell In row.AllocatedCells
                    If cell.ValueType <> CellValueType.Null Then
                        sb.Append(String.Format("{0} [{1}]", cell.Value, cell.ValueType).PadRight(25))
                    Else
                        sb.Append(New String(" "c, 25))
                    End If
                Next
            Next
        Next

        Console.WriteLine(sb.ToString())
    End Sub
End Module

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Download Buy

If you want to try the GemBox.Spreadsheet yourself, you can download the free version. It delivers the same performance and set of features as the professional version, but with some operations limited. To remove the limitation, you need to purchase a license.