How to compare two Word documents and highlight differences using C# in ASP.NET Core?

Syncfusion® DocIO is a .NET Core Word library used to create, read, edit, compare Word documents programmatically without Microsoft Word or interop dependencies. Using this library, you can compare two Word documents and highlight differences using C#.

Steps to compare two Word documents and highlight differences using c#

1. Create a new ASP.NET Core Web application (Model-View-Controller) project.

2. Install the Syncfusion.DocIO.Net.Core NuGet package as a reference to your project from NuGet.org.

3. Include the following namespaces in the HomeController.cs file.

using Syncfusion.DocIO;
using Syncfusion.DocIO.DLS;

4. A default action method named Index will be present in HomeController.cs. Right click on Index method and select Go To View where you will be directed to its associated view page Index.cshtml.

5. Add a new button in the Index.cshtml as shown below.

@{
  Html.BeginForm("CompareWordDocuments", "Home", FormMethod.Get);
  {
      <div>
          <input type="submit" value="Compare Word documents" style="width:200px;height:27px">
      </div>
  }
  Html.EndForm();
}

6. Add a new action method CompareWordDocuments in HomeController.cs and include the below code snippet to compare the two Word documents and highlight differences.

//Loads the original document.
using (FileStream originalDocumentStreamPath = new FileStream("Data/OriginalDocument.docx", FileMode.Open, FileAccess.Read))
{
   using (WordDocument originalDocument = new WordDocument(originalDocumentStreamPath, FormatType.Docx))
   {
       //Loads the revised document.
       using (FileStream revisedDocumentStreamPath = new FileStream("Data/RevisedDocument.docx", FileMode.Open, FileAccess.Read))
       {
           using (WordDocument revisedDocument = new WordDocument(revisedDocumentStreamPath, FormatType.Docx))
           {
               //Compare original document with revised document.
               originalDocument.Compare(revisedDocument, "Nancy Davolio", DateTime.Now.AddDays(-1));
               
               // Create a memory stream to store the comparison result.
               MemoryStream stream = new MemoryStream();

               // Save the compared document into the MemoryStream.
               originalDocument.Save(stream, FormatType.Docx);

               //Download Word document in the browser.
               return File(stream, "application/docx", "Result.docx");

           }
       }
   }
}

A complete working sample to compare two Word documents and highlight differences using C# can be downloaded from GitHub.

By executing the program, you will get the Word document as follows.

Take a moment to peruse the documentation, where you can find basic Word document processing options along with features like mail merge, merge and split documents, find and replace text in the Word document, and most importantly PDF conversion with code examples.

Explore more about the rich set of Syncfusion® Word Framework features.

Conclusion
I hope you enjoyed learning about how to compare two Word document and highlight differences using C# in ASP.NET Core.

You can refer to our ASP.NET Core DocIO feature tour page to know about its other groundbreaking feature representations and documentation, and how to quickly get started for configuration specifications. You can also explore our ASP.NET Core DocIO example to understand how to create and manipulate data.

For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion®, you can try our 30-day free trial to check out our other controls.

If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!