How can IronXL help export Excel files in Blazor Server applications?

IronXL allows developers to create, format, and download Excel files directly from the server in Blazor Server applications, eliminating the need for Microsoft Office.

What steps are required to set up IronXL in a Blazor Server project?

To set up IronXL, create a new Blazor Server project, install IronXL via NuGet, and configure a JavaScript download helper for browser-side file downloads.

How do you create an Excel export service using IronXL in C#?

You can create an Excel export service by writing a dedicated service class that utilizes IronXL to generate and format Excel files, making the code reusable and maintainable.

What is the purpose of the JavaScript download helper in Blazor with IronXL?

The JavaScript download helper in Blazor helps trigger browser downloads by converting byte streams into blob URLs, allowing users to easily download generated Excel files.

How do you integrate IronXL with Blazor components to trigger file downloads?

IronXL integrates with Blazor components by adding a service to the DI container, creating Razor components that call the service for data generation, and passing the generated file byte stream to JavaScript for downloading.

What advanced formatting options does IronXL offer for Excel exports?

IronXL supports advanced formatting options such as conditional formatting, multi-sheet reports, and data validation, enhancing the readability and utility of exported Excel files.

How can IronXL handle large datasets efficiently?

IronXL optimizes large dataset handling by streaming directly to the response, paginating data, using background jobs, and disabling automatic column resizing for efficiency.

What file formats can IronXL work with for Excel files?

IronXL can read and write multiple Excel file formats, including .xlsx, .xls, .csv, and .tsv, allowing flexibility in data integration and export use cases.

What licensing options are available for IronXL?

IronXL offers a free development license for building and testing, with a separate deployment license required for production applications. Various plans are available to meet different needs.

How does IronXL support cross-platform development in .NET applications?

IronXL supports cross-platform development by targeting .NET Standard 2.0, making it compatible with various .NET application types, including Blazor, ASP.NET Core, and more.

The C# Excel Library

Explore IronXL Excel Spreadsheet Library for C# .NET Start Free Trial

Read Excel Files without Interop

See All Code Examples

using IronXL;
using System;
using System.Linq;

// Supported for XLSX, XLS, XLSM, XLTX, CSV and TSV
WorkBook workBook = WorkBook.Load("sample.xlsx");

// Select worksheet at index 0
WorkSheet workSheet = workBook.WorkSheets[0];

// Get any existing worksheet
WorkSheet firstSheet = workBook.DefaultWorkSheet;

// Select a cell and return the converted value
int cellValue = workSheet["A2"].IntValue;

// Read from ranges of cells elegantly.
foreach (var cell in workSheet["A2:A10"])
{
    Console.WriteLine("Cell {0} has value '{1}'", cell.AddressString, cell.Text);
}

// Calculate aggregate values such as Min, Max and Sum
decimal sum = workSheet["A2:A10"].Sum();

// Linq compatible
decimal max = workSheet["A2:A10"].Max(c => c.DecimalValue);

using IronXL;
using System;
using System.Linq;

// Supported for XLSX, XLS, XLSM, XLTX, CSV and TSV
WorkBook workBook = WorkBook.Load("sample.xlsx");

// Select worksheet at index 0
WorkSheet workSheet = workBook.WorkSheets[0];

// Get any existing worksheet
WorkSheet firstSheet = workBook.DefaultWorkSheet;

// Select a cell and return the converted value
int cellValue = workSheet["A2"].IntValue;

// Read from ranges of cells elegantly.
foreach (var cell in workSheet["A2:A10"])
{
    Console.WriteLine("Cell {0} has value '{1}'", cell.AddressString, cell.Text);
}

// Calculate aggregate values such as Min, Max and Sum
decimal sum = workSheet["A2:A10"].Sum();

// Linq compatible
decimal max = workSheet["A2:A10"].Max(c => c.DecimalValue);

PM >Install-Package IronXL.Excel

Install-Package IronXL.Excel

USING IRONXL

How to Export Excel Files in Blazor Using IronXL

Curtis Chau

Updated: August 1, 2026

Exporting data to Excel is something almost every Blazor web application needs -- whether you are generating sales reports, inventory lists, or customer invoices. In a Blazor Server application, accomplishing this reliably without requiring Microsoft Office can feel daunting. IronXL makes it straightforward: you can create, format, and download Excel files directly from the server, with no Office installation required. This guide walks you through building a production-ready Excel export feature in Blazor using IronXL -- from project setup and service design to advanced formatting and multi-sheet reports.

How Do You Set Up IronXL in a Blazor Server Project?

Before writing any export logic, you need to add IronXL to a Blazor Server project and configure a browser-side download helper.

Creating the Blazor Server Project

Start by creating a new Blazor Server project in Visual Studio 2022 or later, targeting .NET 10. Once the project is ready, install IronXL through the NuGet Package Manager Console:

PM > Install-Package IronXL.Excel

Install-Package IronXL.Excel

IronXL works with .NET 6 and later, so existing Blazor projects can adopt it without upgrading the framework. For alternative installation methods -- such as the NuGet UI or CLI -- see the IronXL installation guide.

Adding the JavaScript Download Helper

Blazor Server runs on the server side, so triggering a file download requires a small JavaScript bridge. In your wwwroot folder, add a file called excelExport.js:

window.downloadFileFromStream = async (fileName, contentStreamReference) => {
    const arrayBuffer = await contentStreamReference.arrayBuffer();
    const blob = new Blob([arrayBuffer]);
    const url = URL.createObjectURL(blob);
    const anchorElement = document.createElement('a');
    anchorElement.href = url;
    anchorElement.download = fileName ?? 'export.xlsx';
    anchorElement.click();
    anchorElement.remove();
    URL.revokeObjectURL(url);
}

window.downloadFileFromStream = async (fileName, contentStreamReference) => {
    const arrayBuffer = await contentStreamReference.arrayBuffer();
    const blob = new Blob([arrayBuffer]);
    const url = URL.createObjectURL(blob);
    const anchorElement = document.createElement('a');
    anchorElement.href = url;
    anchorElement.download = fileName ?? 'export.xlsx';
    anchorElement.click();
    anchorElement.remove();
    URL.revokeObjectURL(url);
}

JavaScript

Include this script in your _Host.cshtml file (or App.razor in .NET 8+):

<script src="~/excelExport.js"></script>

<script src="~/excelExport.js"></script>

HTML

This function converts the byte stream from Blazor into a temporary blob URL, triggers the browser download, then cleans up the URL object to prevent memory leaks. It is intentionally minimal -- the heavy lifting happens in C# on the server.

First Step:

How Do You Create an Excel Export Service in C#?

Separating Excel generation from your Razor components keeps the code testable and reusable across multiple pages. The pattern below wraps IronXL inside a dedicated service class.

Building the ExcelExportService

Create a new file Services/ExcelExportService.cs:

using IronXL;
using System.IO;
using ExportExcel.Models;

public class ExcelExportService
{
    public byte[] GenerateSalesReport(List<SalesData> salesData)
    {
        var workbook = WorkBook.Create(ExcelFileFormat.XLSX);
        workbook.Metadata.Author = "Sales Department";

        var worksheet = workbook.CreateWorkSheet("Monthly Sales");

        // Add column headers
        worksheet["A1"].Value = "Date";
        worksheet["B1"].Value = "Product";
        worksheet["C1"].Value = "Quantity";
        worksheet["D1"].Value = "Revenue";
        worksheet["E1"].Value = "Profit Margin";

        // Style the header row
        var headerRange = worksheet["A1:E1"];
        headerRange.Style.Font.Bold = true;
        headerRange.Style.BackgroundColor = "#4472C4";
        headerRange.Style.Font.Color = "#FFFFFF";

        // Populate data rows
        int row = 2;
        foreach (var sale in salesData)
        {
            worksheet[$"A{row}"].Value = sale.Date.ToString("yyyy-MM-dd");
            worksheet[$"B{row}"].Value = sale.Product ?? "Unknown";
            worksheet[$"C{row}"].Value = sale.Quantity;
            worksheet[$"D{row}"].Value = sale.Revenue;
            worksheet[$"E{row}"].Value = $"=D{row}*0.15";
            row++;
        }

        worksheet.AutoSizeColumn(0, true);

        using var ms = workbook.ToStream();
        return ms.ToArray();
    }
}

using IronXL;
using System.IO;
using ExportExcel.Models;

public class ExcelExportService
{
    public byte[] GenerateSalesReport(List<SalesData> salesData)
    {
        var workbook = WorkBook.Create(ExcelFileFormat.XLSX);
        workbook.Metadata.Author = "Sales Department";

        var worksheet = workbook.CreateWorkSheet("Monthly Sales");

        // Add column headers
        worksheet["A1"].Value = "Date";
        worksheet["B1"].Value = "Product";
        worksheet["C1"].Value = "Quantity";
        worksheet["D1"].Value = "Revenue";
        worksheet["E1"].Value = "Profit Margin";

        // Style the header row
        var headerRange = worksheet["A1:E1"];
        headerRange.Style.Font.Bold = true;
        headerRange.Style.BackgroundColor = "#4472C4";
        headerRange.Style.Font.Color = "#FFFFFF";

        // Populate data rows
        int row = 2;
        foreach (var sale in salesData)
        {
            worksheet[$"A{row}"].Value = sale.Date.ToString("yyyy-MM-dd");
            worksheet[$"B{row}"].Value = sale.Product ?? "Unknown";
            worksheet[$"C{row}"].Value = sale.Quantity;
            worksheet[$"D{row}"].Value = sale.Revenue;
            worksheet[$"E{row}"].Value = $"=D{row}*0.15";
            row++;
        }

        worksheet.AutoSizeColumn(0, true);

        using var ms = workbook.ToStream();
        return ms.ToArray();
    }
}

Imports IronXL
Imports System.IO
Imports ExportExcel.Models

Public Class ExcelExportService
    Public Function GenerateSalesReport(salesData As List(Of SalesData)) As Byte()
        Dim workbook = WorkBook.Create(ExcelFileFormat.XLSX)
        workbook.Metadata.Author = "Sales Department"

        Dim worksheet = workbook.CreateWorkSheet("Monthly Sales")

        ' Add column headers
        worksheet("A1").Value = "Date"
        worksheet("B1").Value = "Product"
        worksheet("C1").Value = "Quantity"
        worksheet("D1").Value = "Revenue"
        worksheet("E1").Value = "Profit Margin"

        ' Style the header row
        Dim headerRange = worksheet("A1:E1")
        headerRange.Style.Font.Bold = True
        headerRange.Style.BackgroundColor = "#4472C4"
        headerRange.Style.Font.Color = "#FFFFFF"

        ' Populate data rows
        Dim row As Integer = 2
        For Each sale In salesData
            worksheet($"A{row}").Value = sale.Date.ToString("yyyy-MM-dd")
            worksheet($"B{row}").Value = If(sale.Product, "Unknown")
            worksheet($"C{row}").Value = sale.Quantity
            worksheet($"D{row}").Value = sale.Revenue
            worksheet($"E{row}").Value = $"=D{row}*0.15"
            row += 1
        Next

        worksheet.AutoSizeColumn(0, True)

        Using ms = workbook.ToStream()
            Return ms.ToArray()
        End Using
    End Function
End Class

Imports IronXL
Imports System.IO
Imports ExportExcel.Models

Public Class ExcelExportService
    Public Function GenerateSalesReport(salesData As List(Of SalesData)) As Byte()
        Dim workbook = WorkBook.Create(ExcelFileFormat.XLSX)
        workbook.Metadata.Author = "Sales Department"

        Dim worksheet = workbook.CreateWorkSheet("Monthly Sales")

        ' Add column headers
        worksheet("A1").Value = "Date"
        worksheet("B1").Value = "Product"
        worksheet("C1").Value = "Quantity"
        worksheet("D1").Value = "Revenue"
        worksheet("E1").Value = "Profit Margin"

        ' Style the header row
        Dim headerRange = worksheet("A1:E1")
        headerRange.Style.Font.Bold = True
        headerRange.Style.BackgroundColor = "#4472C4"
        headerRange.Style.Font.Color = "#FFFFFF"

        ' Populate data rows
        Dim row As Integer = 2
        For Each sale In salesData
            worksheet($"A{row}").Value = sale.Date.ToString("yyyy-MM-dd")
            worksheet($"B{row}").Value = If(sale.Product, "Unknown")
            worksheet($"C{row}").Value = sale.Quantity
            worksheet($"D{row}").Value = sale.Revenue
            worksheet($"E{row}").Value = $"=D{row}*0.15"
            row += 1
        Next

        worksheet.AutoSizeColumn(0, True)

        Using ms = workbook.ToStream()
            Return ms.ToArray()
        End Using
    End Function
End Class

Registering the Service

Add the service to the DI container in Program.cs:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddScoped<ExcelExportService>();

var app = builder.Build();
app.MapBlazorHub();
app.MapFallbackToPage("/_Host");
app.Run();

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddScoped<ExcelExportService>();

var app = builder.Build();
app.MapBlazorHub();
app.MapFallbackToPage("/_Host");
app.Run();

Imports Microsoft.AspNetCore.Builder
Imports Microsoft.Extensions.DependencyInjection

Dim builder = WebApplication.CreateBuilder(args)

builder.Services.AddRazorPages()
builder.Services.AddServerSideBlazor()
builder.Services.AddScoped(Of ExcelExportService)()

Dim app = builder.Build()
app.MapBlazorHub()
app.MapFallbackToPage("/_Host")
app.Run()

Imports Microsoft.AspNetCore.Builder
Imports Microsoft.Extensions.DependencyInjection

Dim builder = WebApplication.CreateBuilder(args)

builder.Services.AddRazorPages()
builder.Services.AddServerSideBlazor()
builder.Services.AddScoped(Of ExcelExportService)()

Dim app = builder.Build()
app.MapBlazorHub()
app.MapFallbackToPage("/_Host")
app.Run()

This service demonstrates several key IronXL capabilities. You can create new workbooks and worksheets with a single method call, apply styled headers, populate rows from any data source, and embed Excel formulas such as =D2*0.15. The AutoSizeColumn call ensures columns are wide enough to display their content correctly, regardless of data length. For further formatting options, see the cell styling guide.

How Do You Trigger an Excel Download from a Blazor Component?

Once the service is in place, you need a Razor component that calls it and passes the resulting bytes to the browser.

Writing the Razor Component

Create a page at Pages/ExcelExportDashboard.razor:

@page "/excel-export"
@using ExportExcel.Models
@inject ExcelExportService ExcelService
@inject IJSRuntime JS

<h3>Excel Export Dashboard</h3>

<div class="export-section">
    <button class="btn btn-primary" @onclick="ExportSalesReport" disabled="@isExporting">
        @if (isExporting)
        {
            <span>Generating...</span>
        }
        else
        {
            <span>Export Sales Report</span>
        }
    </button>

    @if (!string.IsNullOrEmpty(errorMessage))
    {
        <div class="alert alert-danger mt-2">@errorMessage</div>
    }
</div>

@code {
    private bool isExporting = false;
    private string errorMessage = "";

    private async Task ExportSalesReport()
    {
        try
        {
            isExporting = true;
            errorMessage = "";

            var salesData = GetSalesData();
            var fileBytes = ExcelService.GenerateSalesReport(salesData);

            using var stream = new MemoryStream(fileBytes);
            using var streamRef = new DotNetStreamReference(stream);
            await JS.InvokeVoidAsync(
                "downloadFileFromStream",
                $"SalesReport_{DateTime.Now:yyyyMMdd}.xlsx",
                streamRef
            );
        }
        catch (Exception)
        {
            errorMessage = "Export failed. Please try again.";
        }
        finally
        {
            isExporting = false;
        }
    }

    private List<SalesData> GetSalesData()
    {
        return new List<SalesData>
        {
            new() { Date = DateTime.Now, Product = "Widget A", Quantity = 100, Revenue = 5000 },
            new() { Date = DateTime.Now.AddDays(-1), Product = "Widget B", Quantity = 75, Revenue = 3750 }
        };
    }
}

@page "/excel-export"
@using ExportExcel.Models
@inject ExcelExportService ExcelService
@inject IJSRuntime JS

<h3>Excel Export Dashboard</h3>

<div class="export-section">
    <button class="btn btn-primary" @onclick="ExportSalesReport" disabled="@isExporting">
        @if (isExporting)
        {
            <span>Generating...</span>
        }
        else
        {
            <span>Export Sales Report</span>
        }
    </button>

    @if (!string.IsNullOrEmpty(errorMessage))
    {
        <div class="alert alert-danger mt-2">@errorMessage</div>
    }
</div>

@code {
    private bool isExporting = false;
    private string errorMessage = "";

    private async Task ExportSalesReport()
    {
        try
        {
            isExporting = true;
            errorMessage = "";

            var salesData = GetSalesData();
            var fileBytes = ExcelService.GenerateSalesReport(salesData);

            using var stream = new MemoryStream(fileBytes);
            using var streamRef = new DotNetStreamReference(stream);
            await JS.InvokeVoidAsync(
                "downloadFileFromStream",
                $"SalesReport_{DateTime.Now:yyyyMMdd}.xlsx",
                streamRef
            );
        }
        catch (Exception)
        {
            errorMessage = "Export failed. Please try again.";
        }
        finally
        {
            isExporting = false;
        }
    }

    private List<SalesData> GetSalesData()
    {
        return new List<SalesData>
        {
            new() { Date = DateTime.Now, Product = "Widget A", Quantity = 100, Revenue = 5000 },
            new() { Date = DateTime.Now.AddDays(-1), Product = "Widget B", Quantity = 75, Revenue = 3750 }
        };
    }
}

Imports ExportExcel.Models
Imports Microsoft.JSInterop

@page "/excel-export"

@inject ExcelExportService ExcelService
@inject IJSRuntime JS

<h3>Excel Export Dashboard</h3>

<div class="export-section">
    <button class="btn btn-primary" @onclick="ExportSalesReport" disabled="@isExporting">
        @If isExporting Then
            <span>Generating...</span>
        Else
            <span>Export Sales Report</span>
        End If
    </button>

    @If Not String.IsNullOrEmpty(errorMessage) Then
        <div class="alert alert-danger mt-2">@errorMessage</div>
    End If
</div>

@code {
    Private isExporting As Boolean = False
    Private errorMessage As String = ""

    Private Async Function ExportSalesReport() As Task
        Try
            isExporting = True
            errorMessage = ""

            Dim salesData = GetSalesData()
            Dim fileBytes = ExcelService.GenerateSalesReport(salesData)

            Using stream As New MemoryStream(fileBytes)
                Using streamRef As New DotNetStreamReference(stream)
                    Await JS.InvokeVoidAsync(
                        "downloadFileFromStream",
                        $"SalesReport_{DateTime.Now:yyyyMMdd}.xlsx",
                        streamRef
                    )
                End Using
            End Using
        Catch ex As Exception
            errorMessage = "Export failed. Please try again."
        Finally
            isExporting = False
        End Try
    End Function

    Private Function GetSalesData() As List(Of SalesData)
        Return New List(Of SalesData) From {
            New SalesData() With {.Date = DateTime.Now, .Product = "Widget A", .Quantity = 100, .Revenue = 5000},
            New SalesData() With {.Date = DateTime.Now.AddDays(-1), .Product = "Widget B", .Quantity = 75, .Revenue = 3750}
        }
    End Function
}

Imports ExportExcel.Models
Imports Microsoft.JSInterop

@page "/excel-export"

@inject ExcelExportService ExcelService
@inject IJSRuntime JS

<h3>Excel Export Dashboard</h3>

<div class="export-section">
    <button class="btn btn-primary" @onclick="ExportSalesReport" disabled="@isExporting">
        @If isExporting Then
            <span>Generating...</span>
        Else
            <span>Export Sales Report</span>
        End If
    </button>

    @If Not String.IsNullOrEmpty(errorMessage) Then
        <div class="alert alert-danger mt-2">@errorMessage</div>
    End If
</div>

@code {
    Private isExporting As Boolean = False
    Private errorMessage As String = ""

    Private Async Function ExportSalesReport() As Task
        Try
            isExporting = True
            errorMessage = ""

            Dim salesData = GetSalesData()
            Dim fileBytes = ExcelService.GenerateSalesReport(salesData)

            Using stream As New MemoryStream(fileBytes)
                Using streamRef As New DotNetStreamReference(stream)
                    Await JS.InvokeVoidAsync(
                        "downloadFileFromStream",
                        $"SalesReport_{DateTime.Now:yyyyMMdd}.xlsx",
                        streamRef
                    )
                End Using
            End Using
        Catch ex As Exception
            errorMessage = "Export failed. Please try again."
        Finally
            isExporting = False
        End Try
    End Function

    Private Function GetSalesData() As List(Of SalesData)
        Return New List(Of SalesData) From {
            New SalesData() With {.Date = DateTime.Now, .Product = "Widget A", .Quantity = 100, .Revenue = 5000},
            New SalesData() With {.Date = DateTime.Now.AddDays(-1), .Product = "Widget B", .Quantity = 75, .Revenue = 3750}
        }
    End Function
}

What the Component Does

The isExporting flag disables the button during generation, preventing duplicate requests. The DotNetStreamReference wrapper handles efficient binary streaming from the .NET memory stream to the JavaScript function -- avoiding large base64 strings that would inflate payload size. Timestamped filenames such as SalesReport_20260228.xlsx keep downloads organized without additional configuration.

When you navigate to /excel-export in the browser, the dashboard page loads with an export button:

Blazor Export to Excel: Complete Guide Using IronXL in C#: Image 1 - Sample Blazor page

Clicking the button generates the spreadsheet and the browser automatically downloads the file:

Blazor Export to Excel: Complete Guide Using IronXL in C#: Image 2 - Data exported to an Excel file

What Advanced Formatting Can You Apply to Excel Exports?

Basic data exports satisfy many use cases, but production applications often need conditional formatting, multiple worksheets, or data validation. IronXL supports all of these natively.

Conditional Formatting for Inventory Reports

The following service highlights low-stock items in red -- a common requirement for warehouse or inventory management applications:

using IronXL;
using ExportExcel.Models;
using System.IO;

public class InventoryExportService
{
    public byte[] GenerateInventoryReport(List<InventoryItem> items)
    {
        var workbook = WorkBook.Create();
        var details = workbook.CreateWorkSheet("Inventory Details");

        // Column headers
        details["A1"].Value = "SKU";
        details["B1"].Value = "Name";
        details["C1"].Value = "Quantity";
        details["D1"].Value = "Reorder Level";
        details["E1"].Value = "Status";

        var headerRange = details["A1:E1"];
        headerRange.Style.Font.Bold = true;
        headerRange.Style.BackgroundColor = "#2E75B6";
        headerRange.Style.Font.Color = "#FFFFFF";

        for (int i = 0; i < items.Count; i++)
        {
            int row = i + 2;
            var item = items[i];

            details[$"A{row}"].Value = item.SKU;
            details[$"B{row}"].Value = item.Name;
            details[$"C{row}"].Value = item.Quantity;
            details[$"D{row}"].Value = item.ReorderLevel;
            details[$"E{row}"].Value = item.Quantity < item.ReorderLevel
                ? "Reorder Required"
                : "OK";

            if (item.Quantity < item.ReorderLevel)
            {
                // Highlight the entire row for low-stock items
                details[$"A{row}:E{row}"].Style.BackgroundColor = "#FFB6B6";
                details[$"C{row}"].Style.Font.Bold = true;
            }
        }

        details.AutoSizeColumn(0, true);
        details.AutoSizeColumn(1, true);

        using var stream = workbook.ToStream();
        return stream.ToArray();
    }
}

using IronXL;
using ExportExcel.Models;
using System.IO;

public class InventoryExportService
{
    public byte[] GenerateInventoryReport(List<InventoryItem> items)
    {
        var workbook = WorkBook.Create();
        var details = workbook.CreateWorkSheet("Inventory Details");

        // Column headers
        details["A1"].Value = "SKU";
        details["B1"].Value = "Name";
        details["C1"].Value = "Quantity";
        details["D1"].Value = "Reorder Level";
        details["E1"].Value = "Status";

        var headerRange = details["A1:E1"];
        headerRange.Style.Font.Bold = true;
        headerRange.Style.BackgroundColor = "#2E75B6";
        headerRange.Style.Font.Color = "#FFFFFF";

        for (int i = 0; i < items.Count; i++)
        {
            int row = i + 2;
            var item = items[i];

            details[$"A{row}"].Value = item.SKU;
            details[$"B{row}"].Value = item.Name;
            details[$"C{row}"].Value = item.Quantity;
            details[$"D{row}"].Value = item.ReorderLevel;
            details[$"E{row}"].Value = item.Quantity < item.ReorderLevel
                ? "Reorder Required"
                : "OK";

            if (item.Quantity < item.ReorderLevel)
            {
                // Highlight the entire row for low-stock items
                details[$"A{row}:E{row}"].Style.BackgroundColor = "#FFB6B6";
                details[$"C{row}"].Style.Font.Bold = true;
            }
        }

        details.AutoSizeColumn(0, true);
        details.AutoSizeColumn(1, true);

        using var stream = workbook.ToStream();
        return stream.ToArray();
    }
}

Imports IronXL
Imports ExportExcel.Models
Imports System.IO

Public Class InventoryExportService
    Public Function GenerateInventoryReport(items As List(Of InventoryItem)) As Byte()
        Dim workbook = WorkBook.Create()
        Dim details = workbook.CreateWorkSheet("Inventory Details")

        ' Column headers
        details("A1").Value = "SKU"
        details("B1").Value = "Name"
        details("C1").Value = "Quantity"
        details("D1").Value = "Reorder Level"
        details("E1").Value = "Status"

        Dim headerRange = details("A1:E1")
        headerRange.Style.Font.Bold = True
        headerRange.Style.BackgroundColor = "#2E75B6"
        headerRange.Style.Font.Color = "#FFFFFF"

        For i As Integer = 0 To items.Count - 1
            Dim row As Integer = i + 2
            Dim item = items(i)

            details($"A{row}").Value = item.SKU
            details($"B{row}").Value = item.Name
            details($"C{row}").Value = item.Quantity
            details($"D{row}").Value = item.ReorderLevel
            details($"E{row}").Value = If(item.Quantity < item.ReorderLevel, "Reorder Required", "OK")

            If item.Quantity < item.ReorderLevel Then
                ' Highlight the entire row for low-stock items
                details($"A{row}:E{row}").Style.BackgroundColor = "#FFB6B6"
                details($"C{row}").Style.Font.Bold = True
            End If
        Next

        details.AutoSizeColumn(0, True)
        details.AutoSizeColumn(1, True)

        Using stream = workbook.ToStream()
            Return stream.ToArray()
        End Using
    End Function
End Class

Imports IronXL
Imports ExportExcel.Models
Imports System.IO

Public Class InventoryExportService
    Public Function GenerateInventoryReport(items As List(Of InventoryItem)) As Byte()
        Dim workbook = WorkBook.Create()
        Dim details = workbook.CreateWorkSheet("Inventory Details")

        ' Column headers
        details("A1").Value = "SKU"
        details("B1").Value = "Name"
        details("C1").Value = "Quantity"
        details("D1").Value = "Reorder Level"
        details("E1").Value = "Status"

        Dim headerRange = details("A1:E1")
        headerRange.Style.Font.Bold = True
        headerRange.Style.BackgroundColor = "#2E75B6"
        headerRange.Style.Font.Color = "#FFFFFF"

        For i As Integer = 0 To items.Count - 1
            Dim row As Integer = i + 2
            Dim item = items(i)

            details($"A{row}").Value = item.SKU
            details($"B{row}").Value = item.Name
            details($"C{row}").Value = item.Quantity
            details($"D{row}").Value = item.ReorderLevel
            details($"E{row}").Value = If(item.Quantity < item.ReorderLevel, "Reorder Required", "OK")

            If item.Quantity < item.ReorderLevel Then
                ' Highlight the entire row for low-stock items
                details($"A{row}:E{row}").Style.BackgroundColor = "#FFB6B6"
                details($"C{row}").Style.Font.Bold = True
            End If
        Next

        details.AutoSizeColumn(0, True)
        details.AutoSizeColumn(1, True)

        Using stream = workbook.ToStream()
            Return stream.ToArray()
        End Using
    End Function
End Class

IronXL applies cell-level formatting based on data values at generation time. You can also apply conditional formatting rules declaratively, or manage multiple worksheets within the same workbook -- for example, one sheet for current stock and another for historical orders.

Adding Multiple Worksheets to a Single Export

Separating data into logical sheets improves readability without requiring separate downloads:

public byte[] GenerateMultiSheetReport(
    List<SalesData> sales,
    List<InventoryItem> inventory)
{
    var workbook = WorkBook.Create(ExcelFileFormat.XLSX);

    // Sheet 1 -- Sales summary
    var salesSheet = workbook.CreateWorkSheet("Sales");
    salesSheet["A1"].Value = "Date";
    salesSheet["B1"].Value = "Revenue";
    salesSheet["A1:B1"].Style.Font.Bold = true;

    for (int i = 0; i < sales.Count; i++)
    {
        salesSheet[$"A{i + 2}"].Value = sales[i].Date.ToString("yyyy-MM-dd");
        salesSheet[$"B{i + 2}"].Value = sales[i].Revenue;
    }

    // Sheet 2 -- Inventory snapshot
    var invSheet = workbook.CreateWorkSheet("Inventory");
    invSheet["A1"].Value = "SKU";
    invSheet["B1"].Value = "Name";
    invSheet["C1"].Value = "Quantity";
    invSheet["A1:C1"].Style.Font.Bold = true;

    for (int i = 0; i < inventory.Count; i++)
    {
        invSheet[$"A{i + 2}"].Value = inventory[i].SKU;
        invSheet[$"B{i + 2}"].Value = inventory[i].Name;
        invSheet[$"C{i + 2}"].Value = inventory[i].Quantity;
    }

    using var stream = workbook.ToStream();
    return stream.ToArray();
}

public byte[] GenerateMultiSheetReport(
    List<SalesData> sales,
    List<InventoryItem> inventory)
{
    var workbook = WorkBook.Create(ExcelFileFormat.XLSX);

    // Sheet 1 -- Sales summary
    var salesSheet = workbook.CreateWorkSheet("Sales");
    salesSheet["A1"].Value = "Date";
    salesSheet["B1"].Value = "Revenue";
    salesSheet["A1:B1"].Style.Font.Bold = true;

    for (int i = 0; i < sales.Count; i++)
    {
        salesSheet[$"A{i + 2}"].Value = sales[i].Date.ToString("yyyy-MM-dd");
        salesSheet[$"B{i + 2}"].Value = sales[i].Revenue;
    }

    // Sheet 2 -- Inventory snapshot
    var invSheet = workbook.CreateWorkSheet("Inventory");
    invSheet["A1"].Value = "SKU";
    invSheet["B1"].Value = "Name";
    invSheet["C1"].Value = "Quantity";
    invSheet["A1:C1"].Style.Font.Bold = true;

    for (int i = 0; i < inventory.Count; i++)
    {
        invSheet[$"A{i + 2}"].Value = inventory[i].SKU;
        invSheet[$"B{i + 2}"].Value = inventory[i].Name;
        invSheet[$"C{i + 2}"].Value = inventory[i].Quantity;
    }

    using var stream = workbook.ToStream();
    return stream.ToArray();
}

Public Function GenerateMultiSheetReport( _
    sales As List(Of SalesData), _
    inventory As List(Of InventoryItem)) As Byte()

    Dim workbook = WorkBook.Create(ExcelFileFormat.XLSX)

    ' Sheet 1 -- Sales summary
    Dim salesSheet = workbook.CreateWorkSheet("Sales")
    salesSheet("A1").Value = "Date"
    salesSheet("B1").Value = "Revenue"
    salesSheet("A1:B1").Style.Font.Bold = True

    For i As Integer = 0 To sales.Count - 1
        salesSheet($"A{i + 2}").Value = sales(i).Date.ToString("yyyy-MM-dd")
        salesSheet($"B{i + 2}").Value = sales(i).Revenue
    Next

    ' Sheet 2 -- Inventory snapshot
    Dim invSheet = workbook.CreateWorkSheet("Inventory")
    invSheet("A1").Value = "SKU"
    invSheet("B1").Value = "Name"
    invSheet("C1").Value = "Quantity"
    invSheet("A1:C1").Style.Font.Bold = True

    For i As Integer = 0 To inventory.Count - 1
        invSheet($"A{i + 2}").Value = inventory(i).SKU
        invSheet($"B{i + 2}").Value = inventory(i).Name
        invSheet($"C{i + 2}").Value = inventory(i).Quantity
    Next

    Using stream = workbook.ToStream()
        Return stream.ToArray()
    End Using
End Function

Public Function GenerateMultiSheetReport( _
    sales As List(Of SalesData), _
    inventory As List(Of InventoryItem)) As Byte()

    Dim workbook = WorkBook.Create(ExcelFileFormat.XLSX)

    ' Sheet 1 -- Sales summary
    Dim salesSheet = workbook.CreateWorkSheet("Sales")
    salesSheet("A1").Value = "Date"
    salesSheet("B1").Value = "Revenue"
    salesSheet("A1:B1").Style.Font.Bold = True

    For i As Integer = 0 To sales.Count - 1
        salesSheet($"A{i + 2}").Value = sales(i).Date.ToString("yyyy-MM-dd")
        salesSheet($"B{i + 2}").Value = sales(i).Revenue
    Next

    ' Sheet 2 -- Inventory snapshot
    Dim invSheet = workbook.CreateWorkSheet("Inventory")
    invSheet("A1").Value = "SKU"
    invSheet("B1").Value = "Name"
    invSheet("C1").Value = "Quantity"
    invSheet("A1:C1").Style.Font.Bold = True

    For i As Integer = 0 To inventory.Count - 1
        invSheet($"A{i + 2}").Value = inventory(i).SKU
        invSheet($"B{i + 2}").Value = inventory(i).Name
        invSheet($"C{i + 2}").Value = inventory(i).Quantity
    Next

    Using stream = workbook.ToStream()
        Return stream.ToArray()
    End Using
End Function

For a full API reference covering workbook properties, range operations, and chart support, visit the IronXL API documentation.

Blazor Export to Excel: Complete Guide Using IronXL in C#: Image 3 - Advanced features example output

How Do You Handle Errors and Large Datasets Efficiently?

Excel export operations can fail silently or degrade performance when datasets are large. The patterns below address both concerns.

Error Handling in the Service Layer

Wrapping generation logic in the service (rather than the component) keeps error handling consistent across all callers. The recommended pattern is to let IronXL exceptions propagate, then wrap them in a domain-specific exception with context about which report failed:

Place a try/catch block around the workbook generation in GenerateSalesReport, catching Exception and rethrowing as InvalidOperationException("Failed to generate sales report", ex). In the Blazor component, catch the InvalidOperationException and display a user-friendly message without exposing internal details. Log the inner exception using ILogger<T> injected into the service constructor, so the development team can trace failures back to a specific workbook operation. Never surface raw exception messages to end users -- file paths, memory addresses, or stack traces can reveal server internals.

See error handling best practices in the official Microsoft documentation for guidance on structured error logging in Blazor. For more guidance on building testable services in .NET, the Microsoft dependency injection documentation explains how to register and resolve scoped services, which is exactly the pattern used here with ExcelExportService.

Performance Considerations for Large Datasets

For datasets exceeding a few thousand rows, consider these approaches:

Excel Export Performance Strategies
Strategy	When to Use	IronXL Support
Stream directly to response	Files >10 MB	`workbook.ToStream()`
Paginate data before export	UI-driven exports with filters	Apply in service before creating workbook
Background job + download link	Reports taking >5 seconds	Combine with SignalR or polling
Disable AutoSizeColumn on large sheets	Sheets with >500 rows	Set fixed column widths instead

IronXL's ToStream() method writes directly to an output stream without loading the entire file into a byte array first, which keeps memory usage lower for large workbooks. For additional performance guidance, see reading and writing large Excel files with IronXL.

What Other Excel Features Does IronXL Support?

Beyond basic export, IronXL provides a wide range of Excel features that cover real-world reporting requirements.

Formulas, Named Ranges, and Number Formatting

You can embed any Excel formula using the same syntax you would type directly into a cell. IronXL evaluates formulas at read time, so consumers of the generated file see calculated results as soon as they open the spreadsheet. Named ranges make formulas more readable and maintainable over time:

// Aggregate formulas on a summary row
worksheet["E2"].Value = "=SUM(D2:D100)";
worksheet["F2"].Value = "=AVERAGE(C2:C100)";
worksheet["G2"].Value = "=COUNTIF(B2:B100,\"Widget A\")";

// Named ranges improve formula readability
worksheet["D2:D100"].Name = "RevenueColumn";
worksheet["E2"].Value = "=SUM(RevenueColumn)";

// Number and date formatting prevents type misinterpretation
worksheet["D2"].Value = 12345.67m;
worksheet["D2"].FormatString = "#,##0.00";
worksheet["A2"].Value = DateTime.Now;
worksheet["A2"].FormatString = "dd/MM/yyyy";

// Aggregate formulas on a summary row
worksheet["E2"].Value = "=SUM(D2:D100)";
worksheet["F2"].Value = "=AVERAGE(C2:C100)";
worksheet["G2"].Value = "=COUNTIF(B2:B100,\"Widget A\")";

// Named ranges improve formula readability
worksheet["D2:D100"].Name = "RevenueColumn";
worksheet["E2"].Value = "=SUM(RevenueColumn)";

// Number and date formatting prevents type misinterpretation
worksheet["D2"].Value = 12345.67m;
worksheet["D2"].FormatString = "#,##0.00";
worksheet["A2"].Value = DateTime.Now;
worksheet["A2"].FormatString = "dd/MM/yyyy";

' Aggregate formulas on a summary row
worksheet("E2").Value = "=SUM(D2:D100)"
worksheet("F2").Value = "=AVERAGE(C2:C100)"
worksheet("G2").Value = "=COUNTIF(B2:B100,""Widget A"")"

' Named ranges improve formula readability
worksheet("D2:D100").Name = "RevenueColumn"
worksheet("E2").Value = "=SUM(RevenueColumn)"

' Number and date formatting prevents type misinterpretation
worksheet("D2").Value = 12345.67D
worksheet("D2").FormatString = "#,##0.00"
worksheet("A2").Value = DateTime.Now
worksheet("A2").FormatString = "dd/MM/yyyy"

' Aggregate formulas on a summary row
worksheet("E2").Value = "=SUM(D2:D100)"
worksheet("F2").Value = "=AVERAGE(C2:C100)"
worksheet("G2").Value = "=COUNTIF(B2:B100,""Widget A"")"

' Named ranges improve formula readability
worksheet("D2:D100").Name = "RevenueColumn"
worksheet("E2").Value = "=SUM(RevenueColumn)"

' Number and date formatting prevents type misinterpretation
worksheet("D2").Value = 12345.67D
worksheet("D2").FormatString = "#,##0.00"
worksheet("A2").Value = DateTime.Now
worksheet("A2").FormatString = "dd/MM/yyyy"

To define named ranges and set the number format explicitly, IronXL exposes both as properties on the range object. This prevents Excel from treating currency values as plain text -- a common issue when exporting financial data from databases that store values as strings.

Supported Excel File Formats

IronXL can read and write multiple Excel formats including .xlsx, .xls, .csv, and .tsv. The format is determined at save time, so the same service class can support both Excel and CSV exports with a small parameter change:

// Export as CSV for systems that consume flat files
workbook.SaveAs("report.csv");

// Or stream as CSV for download
using var ms = workbook.ToStream(ExcelFileFormat.CSV);

// Export as CSV for systems that consume flat files
workbook.SaveAs("report.csv");

// Or stream as CSV for download
using var ms = workbook.ToStream(ExcelFileFormat.CSV);

' Export as CSV for systems that consume flat files
workbook.SaveAs("report.csv")

' Or stream as CSV for download
Using ms As Stream = workbook.ToStream(ExcelFileFormat.CSV)
End Using

' Export as CSV for systems that consume flat files
workbook.SaveAs("report.csv")

' Or stream as CSV for download
Using ms As Stream = workbook.ToStream(ExcelFileFormat.CSV)
End Using

This flexibility matters in integrations where downstream systems -- such as ERP platforms or data warehouses -- expect a specific file format. For a full feature comparison between IronXL and other Excel libraries, visit the IronXL features page.

Microsoft provides a good reference for understanding OOXML file formats if you need to understand the internal structure of .xlsx files when debugging unexpected output. The NuGet package for IronXL is also listed on NuGet.org with full version history and compatibility notes.

How Do You Get Started with IronXL for Blazor Projects?

IronXL is available under a free development license that lets you build and test without any time limit. For production applications, a deployment license is required.

You can download a free trial directly from NuGet -- no registration is needed to start. When you are ready to deploy, review the IronXL licensing options to find the plan that fits the scale of the application.

IronXL works across all major .NET application types -- Blazor Server, Blazor WebAssembly (server-rendered), ASP.NET Core MVC, console applications, and Windows desktop apps. The library targets .NET Standard 2.0, so it is compatible with every supported .NET version from .NET Framework 4.6.2 through .NET 10. If the project also requires PDF generation, IronPDF integrates alongside IronXL with no conflicts, allowing you to export data as either Excel or PDF from the same service layer.

To explore more Blazor-specific examples, see the Blazor Excel export tutorial and the ASP.NET Core export guide. For reading existing spreadsheets, the C# Excel reader tutorial covers common import scenarios. You can also review how to create a new Excel workbook from scratch for projects that need to build files programmatically rather than from templates.

Curtis Chau

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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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