How to Convert XLSX to CSV, JSON, XML and more in C#

How Do I Install the IronXL Library?

First, install IronXL before using it in your applications. IronXL supports .NET MAUI, Blazor, and traditional .NET applications. Use either of these installation methods:

Download: https://ironsoftware.com/csharp/excel/docs/

Or use the NuGet Package Manager:

• Right-click the Solution name in Solution Explorer
• Click Manage NuGet Packages
• Browse for IronXL.Excel
• Install

Install-Package IronXL.Excel

How to Tutorial

How Can I Convert Excel Files to Different Formats?

IronXL provides conversion capabilities that handle complex parsing and formatting automatically.

Add the following code:

:path=/static-assets/excel/content-code-examples/how-to/csharp-convert-xlsx-csv-convert.cs

using IronXL;

// Load an existing Excel workbook
WorkBook workbook = WorkBook.Load("Normal_Excel_File.xlsx");

// Set metadata title for the workbook
workbook.Metadata.Title = "Normal_Excel_File.xlsx";

// Save the workbook in different formats
workbook.SaveAs("XLS_Export.xls");
workbook.SaveAs("XLSX_Export.xlsx");
workbook.SaveAsCsv("CSV_Export.csv");
workbook.SaveAsJson("JSON_Export.json");
workbook.SaveAsXml("XML_Export.xml");

// Convert the workbook to a DataSet, allowing integration with other data tools like DataGridView
System.Data.DataSet dataSet = workbook.ToDataSet();

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The code above loads an XLSX file, adds a Title, then converts it to several formats. When converting to CSV, IronXL handles special characters, multi-line cells, and proper escaping. For JSON exports, it creates a structured object representation of your spreadsheet data. XML conversion preserves cell formatting and data types. Finally, it exports the Worksheet as a DataSet for use with DataGridView objects, which works well when working with DataTables.

Here's another example showing how to convert specific worksheets with custom options:

using IronXL;

// Load workbook and select specific worksheet
WorkBook workbook = WorkBook.Load("MultiSheet.xlsx");
WorkSheet sheet = workbook.WorkSheets["SalesData"];

// Convert just one worksheet to CSV with custom delimiter
sheet.SaveAsCsv("SalesData.csv", delimiter: ";");

// Export to JSON with formatting preserved
var jsonOptions = new JsonSaveOptions
{
    PreserveFormatting = true,
    IncludeHeaders = true
};
sheet.SaveAsJson("SalesData.json", jsonOptions);

// Convert to XML with custom root element
sheet.SaveAsXml("SalesData.xml", "SalesReport");

using IronXL;

// Load workbook and select specific worksheet
WorkBook workbook = WorkBook.Load("MultiSheet.xlsx");
WorkSheet sheet = workbook.WorkSheets["SalesData"];

// Convert just one worksheet to CSV with custom delimiter
sheet.SaveAsCsv("SalesData.csv", delimiter: ";");

// Export to JSON with formatting preserved
var jsonOptions = new JsonSaveOptions
{
    PreserveFormatting = true,
    IncludeHeaders = true
};
sheet.SaveAsJson("SalesData.json", jsonOptions);

// Convert to XML with custom root element
sheet.SaveAsXml("SalesData.xml", "SalesReport");

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For advanced scenarios, you can export to multiple formats simultaneously or handle large files efficiently:

using IronXL;
using System.Threading.Tasks;

// Async conversion for large files
public async Task ConvertLargeFileAsync(string inputPath)
{
    WorkBook workbook = WorkBook.Load(inputPath);

    // Parallel export to multiple formats
    var tasks = new[]
    {
        Task.Run(() => workbook.SaveAsCsv("output.csv")),
        Task.Run(() => workbook.SaveAsJson("output.json")),
        Task.Run(() => workbook.SaveAsXml("output.xml"))
    };

    await Task.WhenAll(tasks);
}

using IronXL;
using System.Threading.Tasks;

// Async conversion for large files
public async Task ConvertLargeFileAsync(string inputPath)
{
    WorkBook workbook = WorkBook.Load(inputPath);

    // Parallel export to multiple formats
    var tasks = new[]
    {
        Task.Run(() => workbook.SaveAsCsv("output.csv")),
        Task.Run(() => workbook.SaveAsJson("output.json")),
        Task.Run(() => workbook.SaveAsXml("output.xml"))
    };

    await Task.WhenAll(tasks);
}

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The various exported files are shown below.

Figure 1 - CSV File Export

Figure 2 - XML Export

Figure 3 - JSON Export

Figure 4 - XLS Export

Figure 5 - Excel Input for all exports

Each conversion format serves different purposes in modern applications. CSV files work well for importing data into databases or data analysis tools. JSON format suits web APIs and JavaScript applications. XML maintains data structure and is commonly used in enterprise systems. The legacy XLS format ensures compatibility with older Excel versions and systems that require backward compatibility.

When working with these conversions, IronXL handles many complexities automatically:

• Character Encoding: Proper UTF-8 encoding for international characters
• Data Type Preservation: Maintains numeric, date, and text formatting
• Formula Evaluation: Calculates formula results before export
• Large File Handling: Efficient memory usage for big spreadsheets
• Error Handling: Graceful handling of corrupted or protected files

For applications requiring high performance or dealing with file size limits, IronXL provides optimization options. You can integrate these conversions into automated workflows, web services, or desktop applications.

Library Quick Access

IronXL API Reference Documentation

Learn more and share how to merge, unmerge, and work with cells in Excel spreadsheets using the handy IronXL API Reference Documentation.

IronXL API Reference Documentation