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

Updated: August 2, 2026

IronXL converts Excel files to multiple formats including JSON, CSV, XML, and older Excel formats like XLS, using simple one-line commands that eliminate manual parsing.

IronXL converts any Excel file into various formats, providing developers with tools to work with Excel in C# without Interop. Whether migrating data between systems, creating data exports for web applications, or integrating with legacy systems, IronXL simplifies the conversion process.

These formats include: JSON for modern web APIs, CSV for data interchange, XML for structured data storage, and older Excel formats such as XLS for backward compatibility. Each format serves specific use cases - CSV works well for database imports, JSON integrates with REST APIs, and XML maintains hierarchical data relationships.

This article demonstrates how to use IronXL to convert to XML, CSV, JSON, and export Excel worksheets as datasets for direct integration with .NET data controls.

Quickstart: Convert an XLSX file to CSV with one line

This example shows how IronXL converts an existing Excel workbook into a CSV file in one line. Load your workbook and save it directly as CSV to get started immediately.

1Install IronXL with NuGet Package Manager
PM > Install-Package IronXL.Excel
```
Install-Package IronXL.Excel
```

2Copy and run this code snippet.

IronXL.WorkBook.Load("input.xlsx").SaveAsCsv("output.csv");

IronXL.WorkBook.Load("input.xlsx").SaveAsCsv("output.csv");

3Deploy to test on your live environment

Start using IronXL in your project today with a free trial

Minimal Workflow (5 steps)

Download C# library to convert XLSX to CSV
Load existing XLSX Excel spreadsheet
Access or modify the workbook
Export to CSV file or several other formats including JSON, TSV, and XML
Check the output files and apply further processing

Step 1

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

PM > Install-Package IronXL.Excel

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:

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();

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();

Imports IronXL

' Load an existing Excel workbook
Dim workbook As 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
Dim dataSet As System.Data.DataSet = workbook.ToDataSet()

Imports IronXL

' Load an existing Excel workbook
Dim workbook As 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
Dim dataSet As System.Data.DataSet = workbook.ToDataSet()

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
sheet.SaveAsJson("SalesData.json");

// Convert to XML
sheet.SaveAsXml("SalesData.xml");

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
sheet.SaveAsJson("SalesData.json");

// Convert to XML
sheet.SaveAsXml("SalesData.xml");

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);
}

Imports IronXL
Imports System.Threading.Tasks

' Async conversion for large files
Public Async Function ConvertLargeFileAsync(inputPath As String) As Task
    Dim workbook As WorkBook = WorkBook.Load(inputPath)
    
    ' Parallel export to multiple formats
    Dim tasks = New Task() {
        Task.Run(Sub() workbook.SaveAsCsv("output.csv")),
        Task.Run(Sub() workbook.SaveAsJson("output.json")),
        Task.Run(Sub() workbook.SaveAsXml("output.xml"))
    }
    
    Await Task.WhenAll(tasks)
End Function

Imports IronXL
Imports System.Threading.Tasks

' Async conversion for large files
Public Async Function ConvertLargeFileAsync(inputPath As String) As Task
    Dim workbook As WorkBook = WorkBook.Load(inputPath)
    
    ' Parallel export to multiple formats
    Dim tasks = New Task() {
        Task.Run(Sub() workbook.SaveAsCsv("output.csv")),
        Task.Run(Sub() workbook.SaveAsJson("output.json")),
        Task.Run(Sub() workbook.SaveAsXml("output.xml"))
    }
    
    Await Task.WhenAll(tasks)
End Function

The various exported files are shown below.

Figure 1

CSV File Export

Figure 2

XML Export

Figure 3

JSON Export

Figure 4

XLS Export

Original Excel XLSX file showing source data with multiple columns and formatting before conversion to various formats

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

Frequently Asked Questions

How can I convert an XLSX file to CSV using IronXL?

With IronXL, you can convert an XLSX file to CSV using a single line of code. Load your workbook with IronXL and save it directly as a CSV file using `WorkBook.Load("input.xlsx").SaveAsCsv("output.csv");`.

What formats can IronXL convert Excel files into?

IronXL can convert Excel files into multiple formats such as CSV, JSON, XML, and XLS. These formats are useful for various applications, including data interchange and legacy system integration.

Does IronXL support Excel conversion in .NET applications?

Yes, IronXL supports conversion in various .NET application frameworks, including .NET MAUI, Blazor, and traditional .NET applications.

Can IronXL handle special characters and multi-line cells during CSV conversion?

Yes, IronXL handles special characters, multi-line cells, and proper data escaping when converting Excel files to CSV format.

Is it possible to convert only specific worksheets using IronXL?

Yes, you can select specific worksheets for conversion in IronXL. Load the workbook, select a worksheet, and save it using methods like `sheet.SaveAsCsv("SalesData.csv")`.

How does IronXL handle formula evaluation in Excel files?

IronXL can evaluate formulas in Excel files before export, ensuring that the final output includes computed values rather than the formula text.

What are the advantages of using JSON format with IronXL?

The JSON format is advantageous for its integration with web APIs and JavaScript applications. IronXL enables conversion of Excel data to JSON, preserving the structured data representation.

How does IronXL ensure compatibility with older Excel versions?

IronXL can export Excel files to the legacy XLS format, maintaining backward compatibility for applications and systems that require older Excel file support.

Can IronXL be used for automated workflows involving Excel file conversions?

Yes, IronXL supports integration into automated workflows and web services, providing efficient and comprehensive conversion solutions for diverse applications.

Does IronXL support large file handling during Excel conversions?

IronXL is optimized for large files, using efficient memory management to process big spreadsheets during conversions while maintaining performance.

Curtis Chau

Chat with engineering team now

Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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