Aspose.Cells  for .NET

Encrypt XLSX Files via C#

Password-protect Excel spreadsheets including XLSX format using .NET Library.

How to Protect XLSX File Using C#

In order to protect XLSX file, we’ll use

Aspose.Cells for .NET

API which is a feature-rich, powerful and easy to use document protection API for C# platform. Open


package manager, search for Aspose.Cells and install. You may also use the following command from the Package Manager Console.


PM> Install-Package Aspose.Cells

Protect XLSX via C#

You need


referenced in your project to execute the following workflow.

  1. Instantiate Workbook class with path to XLSX file
  2. Get the default or any Worksheet to add protection
  3. Protect Worksheet with Worksheet.Protect method
  4. Protect Workbook with Workbook.Protect method
  5. Save result in XLSX format

System Requirements

Aspose.Cells for .NET is supported on all major operating systems. Just make sure that you have the following prerequisites.

  • Microsoft Windows or a compatible OS with .NET Framework, .NET Core, Mono or Xamarin Platforms
  • Development environment like Microsoft Visual Studio
  • Add reference to the Aspose.Cells for .NET DLL in your project


// load the XLSX Excel file 
var book = new Aspose.Cells.Workbook("unlocked.xlsx");

// access the first worksheet
var worksheet = book.Worksheets[0];

// protect the worksheet with password
worksheet.Protect(Aspose.Cells.ProtectionType.All, "password", null);

// protect the whole workbook with password
book.Protect(Aspose.Cells.ProtectionType.All, "password");

// save the modified file in default format
  • About Aspose.Cells for .NET API

    Aspose.Cells API can be used to create, edit, convert and render Microsoft Excel formats to different formats. Moreover, it can be used for comprehensive charting, scalable reporting and reliable calculations within software applications. Aspose.Cells is a standalone API and it does not require any software like Microsoft or OpenOffice.

    Free App to Protect XLSX

    Other Supported Protection Formats

    Using C#, one can easily protect other formats including.

    ODS (OpenDocument Spreadsheet File)
    XLS (Excel Binary Format)
    XLSB (Binary Excel Workbook File)
    XLSM (Spreadsheet File)