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How to ASP to Convert HTML to PDF

Curtis Chau
Curtis Chau
Published:

How Can Developers Convert HTML to PDF in ASP.NET Core?

Struggling to get crisp, pixel-perfect reports and invoices out of your ASP.NET Core app? You're not alone.

Every developer eventually needs to convert dynamic web content—like reports or confirmations—into a reliable, downloadable PDF version. It's a fundamental requirement for generating everything from invoices and detailed reports to secure document formats.

The challenge? Getting that complex HTML, with all its CSS and JavaScript, to render perfectly as a PDF. That's where IronPDF comes in. We've got a powerful .NET PDF library that uses Chrome's rendering engine to simplify the HTML to PDF conversion process, ensuring you get exactly what you see on the screen. You can easily convert even the toughest HTML to PDF file formats with just a few lines of code.

Ready to see how? Let's dive in and look at how we can handle ASP.NET Core HTML to PDF tasks with IronPDF.

Start your free trial and begin converting HTML to PDF documents today.

What Are the Steps to Get Started with IronPDF?

Installing IronPDF in your ASP.NET Core project requires just one command in the NuGet Package Manager Console:

Install-Package IronPdf

This .NET Framework library provides comprehensive HTML rendering capabilities, supporting modern HTML elements, CSS styles, and JavaScript execution. The PDF converter handles complex HTML structures and CSS properties seamlessly. It's essential for managing various document formats.

How to Convert HTML String to PDF Document?

Converting an HTML string directly to a PDF file is straightforward. The following code snippet creates a complete ASP.NET Core controller that converts HTML content to PDF documents:

using Microsoft.AspNetCore.Mvc;
using IronPdf;

namespace HtmlToPdf.Controllers
{
    public class PdfController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }

        [HttpGet]
        public IActionResult ConvertHtmlStringToPdf()
        {
            string htmlContent = @"
<html>
  <head>
    <title>IronPDF Test</title>
    <style>
      body { font-family: Arial; margin: 40px; }
      h1 { color: #2b5797; }
      table { border-collapse: collapse; width: 100%; margin-top: 20px; }
      th, td { border: 1px solid #ccc; padding: 8px; }
      th { background: #f0f0f0; }
    </style>
  </head>
  <body>
    <h1>IronPDF HTML to PDF Test</h1>
    <p>This is a simple test of converting an HTML string to PDF using IronPDF.</p>
    <table>
      <tr><th>Item</th><th>Price</th></tr>
      <tr><td>Apples</td><td>$1.50</td></tr>
      <tr><td>Bananas</td><td>$0.90</td></tr>
    </table>
    <p><em>End of test document.</em></p>
  </body>
</html>";
            // Initialize the PDF converter
            var renderer = new ChromePdfRenderer();
            // Configure default page size and other settings
            renderer.RenderingOptions.PaperSize = IronPdf.Rendering.PdfPaperSize.A4;
            renderer.RenderingOptions.MarginTop = 20;
            renderer.RenderingOptions.MarginBottom = 20;
            // Convert HTML string to PDF document
            var pdfDocument = renderer.RenderHtmlAsPdf(htmlContent);
            // Return PDF file to user, allowing them to download PDF version
            return File(pdfDocument.BinaryData, "application/pdf", "output.pdf");
        }
    }
}
using Microsoft.AspNetCore.Mvc;
using IronPdf;

namespace HtmlToPdf.Controllers
{
    public class PdfController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }

        [HttpGet]
        public IActionResult ConvertHtmlStringToPdf()
        {
            string htmlContent = @"
<html>
  <head>
    <title>IronPDF Test</title>
    <style>
      body { font-family: Arial; margin: 40px; }
      h1 { color: #2b5797; }
      table { border-collapse: collapse; width: 100%; margin-top: 20px; }
      th, td { border: 1px solid #ccc; padding: 8px; }
      th { background: #f0f0f0; }
    </style>
  </head>
  <body>
    <h1>IronPDF HTML to PDF Test</h1>
    <p>This is a simple test of converting an HTML string to PDF using IronPDF.</p>
    <table>
      <tr><th>Item</th><th>Price</th></tr>
      <tr><td>Apples</td><td>$1.50</td></tr>
      <tr><td>Bananas</td><td>$0.90</td></tr>
    </table>
    <p><em>End of test document.</em></p>
  </body>
</html>";
            // Initialize the PDF converter
            var renderer = new ChromePdfRenderer();
            // Configure default page size and other settings
            renderer.RenderingOptions.PaperSize = IronPdf.Rendering.PdfPaperSize.A4;
            renderer.RenderingOptions.MarginTop = 20;
            renderer.RenderingOptions.MarginBottom = 20;
            // Convert HTML string to PDF document
            var pdfDocument = renderer.RenderHtmlAsPdf(htmlContent);
            // Return PDF file to user, allowing them to download PDF version
            return File(pdfDocument.BinaryData, "application/pdf", "output.pdf");
        }
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

Output PDF File

How to ASP.NET Core Convert HTML to PDF: Figure 1 - Simple HTML to PDF output in ASP.NET

This code snippet invokes ImportFromUrl internally when processing web pages. The ChromePdfRenderer class handles the conversion process, transforming HTML code into a properly formatted PDF file. The resultant PDF document maintains all HTML tags, CSS files, and even inline styles from your HTML string directly. This process is crucial for accurately converting PDF pages.

How to Convert HTML Files to PDF Files?

When working with existing HTML files on your server, IronPDF can convert HTML file content while preserving all linked resources. This approach works perfectly for template-based document generation:

using IronPdf;
using Microsoft.AspNetCore.Mvc;
using System.IO;

namespace YourApp.Controllers
{
    public class DocumentController : Controller
    {
        private readonly IWebHostEnvironment _environment;

        public DocumentController(IWebHostEnvironment environment)
        {
            _environment = environment;
        }

        [HttpGet]
        public IActionResult GeneratePdfFromTemplate(string templateName)
        {
            // Get path to HTML file
            string htmlFilePath = Path.Combine(_environment.WebRootPath, "templates", $"{templateName}.html");
            var renderer = new ChromePdfRenderer();
            // Configure rendering options
            renderer.RenderingOptions.EnableJavaScript = true;
            renderer.RenderingOptions.CssMediaType = IronPdf.Rendering.PdfCssMediaType.Print;
            // Convert HTML file to PDF
            var pdf = renderer.RenderHtmlFileAsPdf(htmlFilePath);
            // Add headers and footers if needed
            renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
            {
                Height = 25,
                HtmlFragment = "<div style='text-align:center'>Company Report</div>"
            };
            return File(pdf.BinaryData, "application/pdf", $"{templateName}_generated.pdf");
        }
    }
}
using IronPdf;
using Microsoft.AspNetCore.Mvc;
using System.IO;

namespace YourApp.Controllers
{
    public class DocumentController : Controller
    {
        private readonly IWebHostEnvironment _environment;

        public DocumentController(IWebHostEnvironment environment)
        {
            _environment = environment;
        }

        [HttpGet]
        public IActionResult GeneratePdfFromTemplate(string templateName)
        {
            // Get path to HTML file
            string htmlFilePath = Path.Combine(_environment.WebRootPath, "templates", $"{templateName}.html");
            var renderer = new ChromePdfRenderer();
            // Configure rendering options
            renderer.RenderingOptions.EnableJavaScript = true;
            renderer.RenderingOptions.CssMediaType = IronPdf.Rendering.PdfCssMediaType.Print;
            // Convert HTML file to PDF
            var pdf = renderer.RenderHtmlFileAsPdf(htmlFilePath);
            // Add headers and footers if needed
            renderer.RenderingOptions.HtmlHeader = new HtmlHeaderFooter
            {
                Height = 25,
                HtmlFragment = "<div style='text-align:center'>Company Report</div>"
            };
            return File(pdf.BinaryData, "application/pdf", $"{templateName}_generated.pdf");
        }
    }
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

Output PDF

How to ASP.NET Core Convert HTML to PDF: Figure 2 - HTML template file to PDF

This method reads HTML documents from disk and converts them to PDF files while maintaining the HTML structure. The PDF conversion process preserves all CSS properties, image URLs, and even complex HTML elements. You might also encounter advanced scenarios like setting a specific page width.

How Does IronPDF Handle Web Pages with Forms Authentication?

ASP.NET Core applications often use forms authentication to protect content. When converting HTML documents that require authentication, IronPDF can pass authentication cookies:

[Authorize]
public IActionResult ConvertAuthenticatedPage()
{
    var renderer = new ChromePdfRenderer();
    // Get current URL with authentication
    string currentUrl = $"{Request.Scheme}://{Request.Host}/SecureContent";
    // Pass authentication cookie
    var authCookie = Request.Cookies[".AspNetCore.Cookies"];
    if (!string.IsNullOrEmpty(authCookie))
    {
        renderer.RenderingOptions.CustomCssUrl = currentUrl;
    }
    // Convert authenticated page
    var pdf = renderer.RenderUrlAsPdf(currentUrl);
    return File(pdf.BinaryData, "application/pdf", "secure_document.pdf");
}
[Authorize]
public IActionResult ConvertAuthenticatedPage()
{
    var renderer = new ChromePdfRenderer();
    // Get current URL with authentication
    string currentUrl = $"{Request.Scheme}://{Request.Host}/SecureContent";
    // Pass authentication cookie
    var authCookie = Request.Cookies[".AspNetCore.Cookies"];
    if (!string.IsNullOrEmpty(authCookie))
    {
        renderer.RenderingOptions.CustomCssUrl = currentUrl;
    }
    // Convert authenticated page
    var pdf = renderer.RenderUrlAsPdf(currentUrl);
    return File(pdf.BinaryData, "application/pdf", "secure_document.pdf");
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

This script calling ImportFromUrl recognizes tables, forms, and other HTML content rendered behind authentication. The HTTP status code verification ensures successful page retrieval before PDF conversion. If the URL is invalid or not a URL, the process will fail with an error opening URL. If the URL points to the same virtual directory, resources will be resolved correctly from the specified URL.

What About Converting ASPX Files and Dynamic Content?

For legacy ASPX file conversion or dynamically generated documents, IronPDF handles the rendering process seamlessly. The simple code snippet creates PDF pages from any HTTP or HTTPS address:

public IActionResult ConvertDynamicContent()
{
    var renderer = new ChromePdfRenderer();
    // Enable JavaScript for dynamic content
    renderer.RenderingOptions.EnableJavaScript = true;
    renderer.RenderingOptions.JavascriptDelay = 1000; // Wait for content to load
    // Handle various HTML tags and dynamic elements
    string dynamicHtml = GenerateDynamicHtml(); // Your method
    var pdf = renderer.RenderHtmlAsPdf(dynamicHtml);
    return File(pdf.BinaryData, "application/pdf", "dynamic.pdf");
}
public IActionResult ConvertDynamicContent()
{
    var renderer = new ChromePdfRenderer();
    // Enable JavaScript for dynamic content
    renderer.RenderingOptions.EnableJavaScript = true;
    renderer.RenderingOptions.JavascriptDelay = 1000; // Wait for content to load
    // Handle various HTML tags and dynamic elements
    string dynamicHtml = GenerateDynamicHtml(); // Your method
    var pdf = renderer.RenderHtmlAsPdf(dynamicHtml);
    return File(pdf.BinaryData, "application/pdf", "dynamic.pdf");
}
IRON VB CONVERTER ERROR developers@ironsoftware.com
$vbLabelText   $csharpLabel

Output

How to ASP.NET Core Convert HTML to PDF: Figure 3 - Output PDF file

A common issue in HTML to PDF conversion is ensuring content doesn't create unwanted breaks in HTML. IronPDF minimizes this.

How to Handle CSS Styles and Advanced HTML Rendering?

IronPDF's HTML rendering engine supports advanced CSS styles and HTML5 features. When converting HTML to PDF, the library handles CSS property interpretation, including complex layouts and responsive designs. The PDF programmatically maintains the visual fidelity of your web page, including CSS files, HTML tags, and JavaScript-rendered content.

The conversion process handles blank pages, multiple pages, and page size adjustments automatically. It can also manage specialized scenarios like including headers/footers on odd and even pages or just subsequent odd pages, or handling nonexistent pages gracefully. It's designed to easily convert complex web content.

Why Choose IronPDF for Your .NET Project?

IronPDF stands out as a comprehensive .NET library for HTML to PDF conversion. Unlike basic PDF converters, it provides full support for modern web standards, handling everything from simple HTML strings to complex web applications with forms authentication.

The library excels at converting HTML documents while preserving all formatting, making it ideal for generating professional PDF documents in your .NET Core applications. Whether you need to convert HTML files, process HTML content, or generate PDFs from existing PDF document templates, IronPDF provides the tools necessary for seamless PDF conversion.

Download IronPDF today and transform your HTML content into professional PDF documents with just a few lines of code. For additional support, explore the comprehensive documentation and API reference to unlock the full potential of HTML to PDF conversion in your ASP.NET Core applications.

Frequently Asked Questions

How can I convert HTML to PDF using ASP.NET Core?

You can convert HTML to PDF in ASP.NET Core by using IronPDF, which allows you to convert HTML strings, files, and even authenticated web pages into PDFs with ease.

What are the benefits of using IronPDF for HTML to PDF conversion?

IronPDF provides a comprehensive and developer-friendly API to convert HTML to PDF, offering features such as HTML5 and CSS3 compatibility, support for JavaScript, and the ability to convert complex web pages into professional-quality PDFs.

Can IronPDF handle HTML strings for PDF conversion?

Yes, IronPDF can convert HTML strings directly into PDF documents, making it easy to generate PDFs from dynamically generated content in ASP.NET Core applications.

Is it possible to convert authenticated web pages to PDF using IronPDF?

IronPDF supports converting authenticated web pages by allowing you to pass credentials, making it possible to convert secured content into PDF documents.

Does IronPDF support converting HTML files to PDF?

Yes, IronPDF can convert HTML files into PDF format, providing flexibility in handling various types of HTML content for conversion.

What kind of formatting can IronPDF handle during HTML to PDF conversion?

IronPDF supports advanced formatting capabilities, including CSS styles, JavaScript execution, and the rendering of complex layouts, ensuring the converted PDF closely matches the original HTML layout.

Can I customize the PDF output when using IronPDF?

IronPDF allows extensive customization of the PDF output, including setting headers and footers, customizing page sizes, and controlling margins, ensuring the PDF meets your specific requirements.

What development environments are compatible with IronPDF for HTML to PDF conversion?

IronPDF is compatible with ASP.NET Core and can be used seamlessly within C# projects, making it a versatile tool for developers working in .NET environments.

How does IronPDF ensure the security of the PDF conversion process?

IronPDF can convert HTML to PDF in a secure manner by supporting HTTPS and allowing for the use of authentication credentials, protecting sensitive information during the conversion process.

What are the system requirements for using IronPDF in an ASP.NET Core project?

IronPDF requires a .NET environment and is designed to integrate smoothly into ASP.NET Core applications, ensuring a hassle-free setup and operation for developers.

Curtis Chau
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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