This article explores the most effective methods for PDF creation within the Blazor ecosystem. We will review the most popular libraries, guide you through implementation steps, and compare different approaches to help you choose the one that best fits your needs.

Why Generate PDFs from Blazor Components?

Integrating PDF generation into a Blazor application addresses several critical business needs. The most common use case is report creation. Imagine a dashboard page displaying real-time sales data; users often expect to download a static, shareable version of that report. A PDF ensures that layout, graphics, and data are preserved regardless of the recipient's device or operating system. This is essential for invoices, purchase orders, certificates, or any official document that must have a consistent and professional appearance.

Another major advantage is the ability to generate programmable documents via API endpoints. For example, a third-party system might need to retrieve an invoice for a specific customer by calling a URL like https://yourapi.com/invoices/123/pdf. In this scenario, the PDF is generated on-the-fly on the server without any user interface being displayed. This enables seamless automation of document workflows. The key is to ensure that the resulting PDF is a faithful representation of the corresponding Blazor component, thus creating a unified user experience between what is seen on screen and what is downloaded.

Fundamental Approaches: Integrated Libraries or Dedicated APIs

To transform your Blazor pages into PDFs, two main strategies are available: integrate a .NET library directly into your project or use a dedicated PDF service API. Each has its pros and cons.

1. Integrate a .NET library: This approach gives you full control over the conversion process. Libraries like Syncfusion, IronPDF, or QuestPDF are added to your project via NuGet. You interact with them directly in your C# code. This is an excellent option if your application needs to run in an isolated environment or if you have very specific customization requirements. However, this method can increase your application's complexity, consume significant server resources (especially for heavy conversions), and sometimes incur licensing costs. Additionally, compatibility can be an issue, as many powerful libraries only work on Blazor Server and not on WebAssembly (WASM).
2. Use a PDF service API: The alternative is to delegate PDF generation to an external cloud service. This "API-first" approach greatly simplifies your architecture. Instead of running a heavy rendering engine on your own server, you simply send the HTML content or a URL to an API endpoint and receive a PDF file in return. This is a highly scalable solution, ideal for handling high conversion volumes or complex tasks. Platforms like ours, PDFWizard.io, offer not only conversion but also a full suite of tools for editing, securing, and optimizing PDFs, all accessible via a simple REST API. The main drawback is the need for an internet connection and a subscription model.

The choice between these two approaches depends on your project constraints, performance needs, and desired features beyond simple conversion.

The Best Libraries for PDF Generation in Blazor

Several .NET libraries have established themselves as go-to solutions for HTML to PDF conversion in Blazor applications. Choosing the right library depends on your specific use case, budget, and required rendering fidelity.

Syncfusion HTML to PDF Converter

Syncfusion's library is a robust and widely used solution in the .NET ecosystem. It is specifically designed to accurately convert web pages or raw HTML strings into PDF documents. It excels at preserving complex layouts, CSS styles, images, SVGs, and even web fonts.

Main features include:

• Conversion of URLs, HTML files, or raw HTML strings.
• Support for HTML headers and footers.
• Options to customize page size, orientation, and margins.
• Ability to add bookmarks, tables of contents, and manage pagination.

Implementation in a Blazor Server app typically follows a simple pattern: install the NuGet package, create an export service to encapsulate conversion logic, inject it into your Razor component, then use JavaScript interop to trigger the download of the generated file in the user's browser.

IronPDF

IronPDF is another leading commercial library, often praised for its "pixel-perfect" rendering. Its strength lies in using an embedded Chrome rendering engine, meaning "what you see in Chrome is what you get in the PDF." This makes it an excellent choice if visual fidelity with an existing web page is your top priority.

Advantages include:

• Excellent support for CSS3, HTML5, and JavaScript.
• Ability to fill and submit forms before conversion.
• Security features to protect, sign, and set permissions on PDFs.
• Allows extraction of text and images from existing PDFs.

Similar to Syncfusion, integration involves installing a NuGet package and calling its conversion methods from your C# code. It is a powerful solution for those needing high-quality C# HTML to PDF conversion.

QuestPDF

Unlike IronPDF and Syncfusion, QuestPDF is an open-source and free library that takes a different approach. Instead of converting existing HTML, QuestPDF lets you compose a PDF document using a fluent C# API. You describe the document structure (headers, columns, tables, images) programmatically.

// Example of QuestPDF fluent syntax
document.Page(page =>
{
    page.Header()
        .Text("Invoice #2024-001")
        .SemiBold().FontSize(20);

    page.Content()
        .Column(column =>
        {
            column.Item().Table(table =>
            {
                // Define table columns and rows...
            });
        });

    page.Footer()
        .AlignCenter()
        .Text(x =>
        {
            x.Span("Page ");
            x.CurrentPageNumber();
        });
});

This method is ideal for generating highly structured documents like invoices, catalogs, or reports where the layout is well-defined and does not need to match an existing web page. It is more verbose than simple HTML conversion but offers full control over every document element and exceptional performance since it does not require a browser rendering engine.

Step-by-Step Guide: Converting a Blazor Page to PDF

Here is a generic approach, inspired by best practices, to implement PDF generation in a Blazor Server application. Specific steps may vary slightly depending on the library you choose, but the concepts remain the same.

1. Project Setup

Start by creating a new Blazor Server app in Visual Studio or via the .NET CLI. Then, the first step is to add your chosen PDF conversion library to your project. You can do this via the NuGet package manager:

# Example with a hypothetical library
dotnet add package Your.Chosen.PdfLibrary

Don't forget to check the library documentation for any license packages or additional dependencies.

2. Creating a PDF Generation Service

To keep your code clean and reusable, it is recommended to encapsulate conversion logic in a dedicated service class. Create a new file, for example PdfExportService.cs, in your Data folder.

using Your.Chosen.PdfLibrary;
using System.IO;

public class PdfExportService
{
    public MemoryStream ConvertUrlToPdf(string url)
    {
        // Initialize the library's converter
        var htmlConverter = new HtmlToPdfConverter();
        
        // Configure options (page size, margins, etc.) if needed
        // converter.Settings.PageSize = PdfPageSize.A4;

        // Convert the URL to a PDF document
        PdfDocument document = htmlConverter.Convert(url);

        // Save the document to a memory stream
        var stream = new MemoryStream();
        document.Save(stream);
        stream.Position = 0; // Reset stream position
        
        return stream;
    }
}

This service contains a method that takes a URL as input and returns the generated PDF as a MemoryStream.

3. Injecting and Calling the Service

Now you need to make this service available in your app and call it from a Razor component. First, register the service in Program.cs (or Startup.cs for older projects):

// In Program.cs
builder.Services.AddScoped(); 

Then, in the Razor component from which you want to trigger the export (e.g., FetchData.razor), inject the service along with NavigationManager to get the current URL and IJSRuntime to interact with JavaScript.

@page "/fetchdata"
@inject PdfExportService exportService
@inject NavigationManager NavigationManager
@inject IJSRuntime JSRuntime

Weather forecast


Export to PDF

@code {
    private string currentUrl;

    protected override void OnInitialized()
    {
        currentUrl = NavigationManager.Uri;
    }

    private async Task ExportToPdf()
    {
        // Call the service to generate the PDF
        using (MemoryStream pdfStream = exportService.ConvertUrlToPdf(currentUrl))
        {
            // Use JS interop to download the file
            var fileName = "Report.pdf";
            var fileBytes = pdfStream.ToArray();
            await JSRuntime.InvokeVoidAsync("saveAsFile", fileName, Convert.ToBase64String(fileBytes));
        }
    }
}

4. Handling File Download with JS Interop

Server-side C# code cannot directly trigger a file download in the browser. To do this, we must use JavaScript interoperability. In your _Host.cshtml (or _Layout.cshtml), add the following JavaScript function. It creates an in-memory link, clicks it to start the download, then removes it.

This script is the final piece of the puzzle. When the user clicks the "Export to PDF" button, the C# code generates the PDF, converts it to a Base64 string, and calls this JavaScript function so the browser shows a download dialog. This interaction between C# and JS is fundamental in Blazor Server, and understanding how to convert JavaScript to PDF or, in this case, use JS to serve a PDF generated by C#, is a key skill.

The API-First Alternative: Using a Cloud Service

If managing libraries, dependencies, and server load seems tedious, an API-first approach offers an elegant and powerful alternative. Instead of embedding conversion logic, you offload it to a specialized service.

Why Choose a PDF API?

Using an API like ours at PDFWizard.io offers several strategic advantages:

• Simplified maintenance: You no longer worry about library updates, security patches, or dependencies. The API provider handles it for you.
• Reduced server load: The most resource-intensive task, HTML rendering, is performed on optimized infrastructure, freeing your own server's resources.
• Advanced features at your fingertips: API services often go far beyond simple conversion. You can access features such as:
  • Optical Character Recognition (OCR) to make scanned PDFs searchable.
  • Merging to combine multiple HTML files into a single PDF.
  • Splitting, compression, encryption, and watermarking.
  • Online editing to add text, shapes, or signatures.
• Platform independence: A REST API works identically whether called from Blazor Server, Blazor WASM, a desktop app, or a mobile app. It is the most flexible solution if you need to convert HTML to PDF on Mac or any other platform without worrying about OS dependencies.

Example Workflow with an API

Integrating a PDF API into your Blazor code is remarkably simple. It essentially involves making an HTTP request.

// Conceptual example of calling a PDF API
public class PdfApiService
{
    private readonly HttpClient _httpClient;

    public PdfApiService(HttpClient httpClient)
    {
        _httpClient = httpClient;
        // Configure HTTP client with base URL and API key
        _httpClient.BaseAddress = new Uri("https://api.pdfwizard.io/v1/");
        _httpClient.DefaultRequestHeaders.Add("Authorization", "Bearer YOUR_API_KEY");
    }

    public async Task ConvertHtmlToPdfAsync(string htmlContent)
    {
        var requestData = new { html = htmlContent };
        var response = await _httpClient.PostAsJsonAsync("convert/html", requestData);

        response.EnsureSuccessStatusCode();

        return await response.Content.ReadAsByteArrayAsync();
    }
}

In this model, your service injects HttpClient, configures authentication, and sends the HTML content in the body of a POST request. The API returns the raw PDF bytes, which you can then serve to the user just like with the library method, using JavaScript interoperability.

This approach is especially powerful for batch processes. Our "Batch" mode lets you submit up to 50 documents and apply the same action in series, saving considerable time for back-office operations. Additionally, for compliance-conscious businesses, we process files on a European GDPR-compliant infrastructure, and no data is retained beyond 60 minutes by default, ensuring security and privacy.

Choosing the right method to generate PDFs from Blazor depends entirely on your project's requirements. For full control and simple scenarios within a Blazor Server app, integrating a .NET library like Syncfusion or IronPDF is a solid, proven path. For structured documents where layout is code-defined, QuestPDF's composition approach offers unmatched flexibility and performance.

However, as your needs evolve toward greater scale, advanced features, or cross-platform compatibility (including Blazor WASM), an API-first approach becomes increasingly attractive. By offloading PDF conversion and manipulation to a specialized service like ours, you simplify your architecture, reduce server load, and gain access to a comprehensive toolkit for your document lifecycle. The final decision balances control, convenience, cost, and features.