Compare Excel Files via REST in C#

Mon, 21 Sep 2026 11:32:39 +0000

Analyzing changes between spreadsheet versions is a routine task for finance, reporting, and data‑validation workflows. GroupDocs.Comparison Cloud SDK for .NET provides a powerful API that makes it easy to compare Excel files in .NET without manual inspection. In this guide you will see how to set up the library, upload workbooks, call the REST endpoint from C#, retrieve detailed change information, and fine‑tune comparison options for precise results.

Before You Start: Prerequisites and Installation

Before you begin, ensure you have the following:

.NET 6.0 or later installed.
An IDE such as Visual Studio 2022.
A GroupDocs Cloud account with ClientId and ClientSecret.
Access to the GroupDocs Cloud storage where the Excel files will be uploaded.

Install the SDK via NuGet:

dotnet add package GroupDocs.Comparison-Cloud

Download the latest package from the release page. After installation, add your credentials in code as shown later. You are now ready to start the comparison workflow.

Step-by-Step Guide to Compare Excel Files in .NET

The following steps illustrate how to compare Excel files in .NET using the SDK.

Step 1: Load the Source and Target Documents

Create a configuration object with your credentials and instantiate the CompareApi.

var config = new Configuration
{
    ClientId = "YOUR_CLIENT_ID",
    ClientSecret = "YOUR_CLIENT_SECRET"
};

var compareApi = new CompareApi(config);

Step 2: Prepare the Excel Workbooks

Define FileInfo objects that point to the source and target XLSX files stored in GroupDocs Cloud storage.

var sourceFile = new FileInfo { FilePath = "input/source.xlsx" };
var targetFile = new FileInfo { FilePath = "input/target.xlsx" };

Step 3: Set Comparison Options and Settings

Configure the CompareOptions object, including detailed change settings.

var compareOptions = new CompareOptions
{
    SourceFile = sourceFile,
    TargetFiles = new List { targetFile },
    OutputPath = "output/diff_result.xlsx",
    Settings = new Settings
    {
        ShowDeletedContent = true,
        ShowInsertedContent = true,
        ShowStyleChanges = true,
        GenerateSummaryPage = true
    }
};

For a full list of settings, refer to the API reference.

Step 4: Execute the Comparison and Process Results

Call the Compare method and read the basic result information.

var compareResult = compareApi.Compare(compareOptions);
Console.WriteLine($"Comparison completed. Result file: {compareResult.Path}");
Console.WriteLine($"Number of changes detected: {compareResult.Changes?.Count ?? 0}");

Step 5: Retrieve Detailed Change Information

If you need a granular report, use the GetChanges request.

var changesRequest = new GetChangesRequest
{
    SourceFile = sourceFile,
    TargetFile = targetFile,
    OutputPath = "output/detailed_changes.json"
};
var detailedChanges = compareApi.GetChanges(changesRequest);
Console.WriteLine($"Detailed changes saved to: {detailedChanges.Path}");

With these steps you have fully automated the process of comparing Excel files in .NET.

Comparing Excel Files Programmatically - Complete Code Example

The following code demonstrates the complete workflow from configuration to result handling.

using System;
using System.Collections.Generic;
using GroupDocs.Comparison.Cloud.Sdk.Api;
using GroupDocs.Comparison.Cloud.Sdk.Client;
using GroupDocs.Comparison.Cloud.Sdk.Model;

namespace CompareExcelDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            // Set up API credentials (replace with your actual credentials)
            var config = new Configuration
            {
                ClientId = "YOUR_CLIENT_ID",
                ClientSecret = "YOUR_CLIENT_SECRET"
            };

            // Initialize Compare API
            var compareApi = new CompareApi(config);

            // Prepare source and target Excel files (must be uploaded to GroupDocs Cloud storage beforehand)
            var sourceFile = new FileInfo { FilePath = "input/source.xlsx" };
            var targetFile = new FileInfo { FilePath = "input/target.xlsx" };

            // Define comparison options
            var compareOptions = new CompareOptions
            {
                SourceFile = sourceFile,
                TargetFiles = new List { targetFile },
                OutputPath = "output/diff_result.xlsx",
                // Optional: specify that we want detailed changes for worksheets
                Settings = new Settings
                {
                    ShowDeletedContent = true,
                    ShowInsertedContent = true,
                    ShowStyleChanges = true,
                    GenerateSummaryPage = true
                }
            };

            try
            {
                // Call the Compare API
                var compareResult = compareApi.Compare(compareOptions);

                // Output basic result information
                Console.WriteLine($"Comparison completed. Result file: {compareResult.Path}");
                Console.WriteLine($"Number of changes detected: {compareResult.Changes?.Count ?? 0}");

                // Iterate through change details
                if (compareResult.Changes != null)
                {
                    foreach (var change in compareResult.Changes)
                    {
                        Console.WriteLine("--------------------------------------------------");
                        Console.WriteLine($"Change Type   : {change.ChangeType}");
                        Console.WriteLine($"Worksheet     : {change.Worksheet}");
                        Console.WriteLine($"Cell Address  : {change.CellAddress}");
                        Console.WriteLine($"Old Value     : {change.OldValue}");
                        Console.WriteLine($"New Value     : {change.NewValue}");
                        Console.WriteLine($"Is New Row    : {change.IsNewRow}");
                        Console.WriteLine($"Is New Column : {change.IsNewColumn}");
                    }
                }

                // Retrieve detailed changes via GetChanges (optional)
                var changesRequest = new GetChangesRequest
                {
                    SourceFile = sourceFile,
                    TargetFile = targetFile,
                    OutputPath = "output/detailed_changes.json"
                };
                var detailedChanges = compareApi.GetChanges(changesRequest);
                Console.WriteLine($"Detailed changes saved to: {detailedChanges.Path}");
            }
            catch (ApiException apiEx)
            {
                Console.WriteLine($"API error: {apiEx.ErrorCode} - {apiEx.Message}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Unexpected error: {ex.Message}");
            }
        }
    }
}

Note: This code example demonstrates the core functionality. Before using it in your project, make sure to update any file paths and configuration values to match your actual environment, verify that all required dependencies are properly installed, and test thoroughly in your development environment. If you encounter any issues, please refer to the official documentation or reach out to the support team for assistance.

Perform Excel Comparison via REST with cURL

You can achieve the same result without writing C# code by calling the REST API directly.

1. Authenticate and Get Access Token

curl -X POST "https://api.groupdocs.cloud/v1.0/oauth2/token" \
     -H "Content-Type: application/json" \
     -d '{"client_id":"YOUR_CLIENT_ID","client_secret":"YOUR_CLIENT_SECRET"}'

2. Upload the Source Workbook

curl -X PUT "https://api.groupdocs.cloud/v1.0/storage/file?path=input/source.xlsx" \
     -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
     -T "./source.xlsx"

3. Upload the Target Workbook

curl -X PUT "https://api.groupdocs.cloud/v1.0/storage/file?path=input/target.xlsx" \
     -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
     -T "./target.xlsx"

4. Execute the Comparison

curl -X POST "https://api.groupdocs.cloud/v1.0/comparison/compare" \
     -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
     -H "Content-Type: application/json" \
     -d '{
           "source_file": {"file_path":"input/source.xlsx"},
           "target_files": [{"file_path":"input/target.xlsx"}],
           "output_path":"output/diff_result.xlsx",
           "settings": {
               "show_deleted_content": true,
               "show_inserted_content": true,
               "show_style_changes": true,
               "generate_summary_page": true
           }
         }'

5. Download the Resulting Diff Workbook

curl -X GET "https://api.groupdocs.cloud/v1.0/storage/file?path=output/diff_result.xlsx" \
     -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
     -o diff_result.xlsx

For a complete list of parameters, see the official API documentation.

Conclusion

Using the GroupDocs.Comparison Cloud SDK for .NET you can easily compare Excel files in .NET and obtain a detailed diff workbook that highlights every modification. The SDK’s REST‑based architecture lets you integrate spreadsheet comparison into any C# service, web API, or background job with minimal effort. Remember to acquire a proper license for production use; a temporary license is available from the license page and full licensing details are listed on the product site. Start automating your Excel diff workflows today and eliminate manual inspection errors.

FAQs

How can I compare Excel files in .NET without writing a lot of code?
The SDK abstracts the heavy lifting. You only need to configure credentials, point to the two XLSX files, and call compareApi.Compare. The library returns a diff file and a list of change objects.
What format does the diff result use?
By default the result is saved as an XLSX workbook, preserving the original layout while applying visual markers for deletions, insertions, and style changes.
Is it possible to compare protected Excel workbooks?
Yes. Provide the password in the FileInfo object’s Password property. The API will unlock the workbook before performing the comparison.
Do I need a license for development and testing?
A temporary license can be obtained from the license page. For production deployments you must purchase a full license as described on the product page.

csharp rest api on Document Processing REST APIs | GroupDocs Cloud