Why is prettifying HTML important before converting to PDF?

Prettifying HTML ensures the content is structured and visually coherent, which reduces rendering issues and enhances the readability and quality of the final PDF produced by IronPDF.

What libraries can be used in .NET to prettify HTML?

Libraries like HtmlAgilityPack, AngleSharp, and online tools like BeautifyTools can be used to prettify HTML in .NET, helping to clean and format code for better readability.

How does IronPDF handle JavaScript and interactive elements?

IronPDF supports JavaScript execution, enabling interactive elements in the generated PDFs, thus making it suitable for dynamic and interactive document needs.

What advantages does using an online HTML beautifier provide?

Using an online HTML beautifier, like BeautifyTools, allows you to quickly and easily reformat HTML code for better readability without needing to install any software or libraries.

What are some key features of IronPDF?

Key features of IronPDF include full HTML5 and CSS3 support, JavaScript execution, support for headers, footers, and watermarks, PDF signing and security features, as well as efficient performance with multi-threaded processing.

How can HtmlAgilityPack be used to format HTML?

HtmlAgilityPack can parse and manipulate HTML documents by loading the HTML content into an HtmlDocument object, then saving it with indentation to make it prettified.

How can you convert prettified HTML to PDF using IronPDF?

Once HTML is prettified using a library like AngleSharp, you can convert it to PDF by using IronPDF's ChromePdfRenderer, which takes the formatted HTML file and produces a high-quality PDF document.

The C# PDF Library

Q: How does IronPDF support modern web standards?

IronPDF fully supports modern web standards like HTML5, CSS3, and JavaScript, ensuring that rendered PDFs maintain their intended design and layout accurately.

Q: Why should developers integrate an HTML prettifier with IronPDF?

Integrating an HTML prettifier with IronPDF ensures that documents are not only visually appealing but also free of rendering issues, enhancing workflow efficiency and document quality.

Explore IronPDF Start Free Trial

HTML to PDF

Online Demo See All Code Examples

using IronPdf;

// Disable local disk access or cross-origin requests
Installation.EnableWebSecurity = true;

// Instantiate Renderer
var renderer = new ChromePdfRenderer();

// Create a PDF from a HTML string using C#
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");

// Export to a file or Stream
pdf.SaveAs("output.pdf");

// Advanced Example with HTML Assets
// Load external html assets: Images, CSS and JavaScript.
// An optional BasePath 'C:\site\assets\' is set as the file location to load assets from
var myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", @"C:\site\assets\");
myAdvancedPdf.SaveAs("html-with-assets.pdf");

using IronPdf;

// Disable local disk access or cross-origin requests
Installation.EnableWebSecurity = true;

// Instantiate Renderer
var renderer = new ChromePdfRenderer();

// Create a PDF from a HTML string using C#
var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>");

// Export to a file or Stream
pdf.SaveAs("output.pdf");

// Advanced Example with HTML Assets
// Load external html assets: Images, CSS and JavaScript.
// An optional BasePath 'C:\site\assets\' is set as the file location to load assets from
var myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", @"C:\site\assets\");
myAdvancedPdf.SaveAs("html-with-assets.pdf");

PM >Install-Package IronPdf

Install-Package IronPdf

.NET HELP

HTML Prettifier (How it Works for Developers)

Jacob Mellor

Updated: August 1, 2026

When working with HTML-to-PDF conversion in .NET, clean and well-structured HTML can make a significant difference in the quality of the final PDF. Formatting raw HTML properly ensures readability, correct rendering, and consistency. This is where an HTML formatter, or an HTML prettifier, comes into play.

In this article, we'll explore how to use an HTML prettifier in .NET before converting HTML to PDF using IronPDF. We'll discuss the benefits of prettification, showcase libraries that can help, and provide a practical code example.

What is an HTML Prettifier?

An HTML prettifier is a tool that reformats raw or minified HTML code into a readable, well-structured format. This process involves:

Properly indenting nested elements
Closing unclosed tags
Formatting attributes consistently
Removing unnecessary whitespace

Using an HTML prettifier before converting to PDF ensures that the content remains structured and visually coherent, reducing rendering issues in the generated PDF.

IronPDF: A Powerful PDF Solution

HTML Prettifier (How it Works for Developers): Figure 1

IronPDF is a comprehensive and feature-rich .NET library designed for seamless HTML-to-PDF conversion. It enables developers to convert HTML, URLs, or even raw HTML strings into high-quality PDFs with minimal effort. Unlike many other PDF libraries, IronPDF fully supports modern web standards, including HTML5, CSS3, and JavaScript, ensuring that rendered PDFs maintain their intended design and layout. This makes it an ideal choice for projects requiring precise PDF output from complex HTML structures.

Some of the key features of IronPDF include:

Full HTML5 and CSS3 support for accurate rendering.
JavaScript execution, enabling interactive elements in PDFs.
Support for headers, footers, and watermarks to enhance document structure.
PDF signing and security features for secure document handling.
Efficient performance with multi-threaded processing and optimized rendering.

By integrating IronPDF with an HTML prettifier, you ensure that your documents are not only visually appealing but also free of rendering issues, making your workflow smoother and more efficient.

Prettifying HTML in .NET

There are several libraries available in .NET to prettify unformatted or ugly HTML code, including:

1. HtmlAgilityPack

A popular library for parsing and modifying HTML code in C#.
Can be used to format and clean up HTML code before processing.

2. AngleSharp

A modern HTML parser for .NET that provides detailed document manipulation capabilities.
Can format HTML in a way that makes it more readable.

3. HTML Beautifier (BeautifyTools)

Formats and indents messy HTML for better readability.
Online Tool that works directly in the browser - no installation required.

Using HtmlAgilityPack to Format HTML Code

HTML Prettifier (How it Works for Developers): Figure 2

HtmlAgilityPack is a popular .NET library that provides a fast and efficient way to parse and manipulate HTML documents. It can handle malformed or poorly structured HTML, making it a great choice for web scraping and data extraction. Although it's not explicitly designed as a "prettifier," it can be used to clean and format HTML code by parsing and saving it with proper indentation.

Here's how you can use HtmlAgilityPack to prettify HTML before passing it to IronPDF:

using IronPdf;
using HtmlAgilityPack;
using System.IO;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";

        // Load the HTML content into an HtmlDocument
        HtmlDocument doc = new HtmlDocument();
        doc.LoadHtml(htmlContent);

        // Prettify the HTML by saving it with indentation
        // Saves the formatted HTML with the prettified indenting
        string prettyHtml = doc.DocumentNode.OuterHtml;
        doc.Save("pretty.html"); // Save the pretty HTML to a file
    }
}

using IronPdf;
using HtmlAgilityPack;
using System.IO;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";

        // Load the HTML content into an HtmlDocument
        HtmlDocument doc = new HtmlDocument();
        doc.LoadHtml(htmlContent);

        // Prettify the HTML by saving it with indentation
        // Saves the formatted HTML with the prettified indenting
        string prettyHtml = doc.DocumentNode.OuterHtml;
        doc.Save("pretty.html"); // Save the pretty HTML to a file
    }
}

Imports IronPdf
Imports HtmlAgilityPack
Imports System.IO

Friend Class Program
	Shared Sub Main()
		Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>"

		' Load the HTML content into an HtmlDocument
		Dim doc As New HtmlDocument()
		doc.LoadHtml(htmlContent)

		' Prettify the HTML by saving it with indentation
		' Saves the formatted HTML with the prettified indenting
		Dim prettyHtml As String = doc.DocumentNode.OuterHtml
		doc.Save("pretty.html") ' Save the pretty HTML to a file
	End Sub
End Class

Imports IronPdf
Imports HtmlAgilityPack
Imports System.IO

Friend Class Program
	Shared Sub Main()
		Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>"

		' Load the HTML content into an HtmlDocument
		Dim doc As New HtmlDocument()
		doc.LoadHtml(htmlContent)

		' Prettify the HTML by saving it with indentation
		' Saves the formatted HTML with the prettified indenting
		Dim prettyHtml As String = doc.DocumentNode.OuterHtml
		doc.Save("pretty.html") ' Save the pretty HTML to a file
	End Sub
End Class

Output HTML File

HTML Prettifier (How it Works for Developers): Figure 3

Using AngleSharp as an HTML Prettifier

HTML Prettifier (How it Works for Developers): Figure 4

AngleSharp is a .NET library designed for parsing and manipulating HTML, XML, and SVG documents. It provides a modern and flexible approach to DOM manipulation and formatting. AngleSharp's HtmlFormatter class can be used to format HTML content, providing nice, readable output.

using AngleSharp.Html.Parser;
using System;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";

        // Parse the HTML content using HtmlParser
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);

        // Format the HTML using AngleSharp’s HtmlFormatter
        var prettyHtml = document.ToHtml();
    }
}

using AngleSharp.Html.Parser;
using System;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";

        // Parse the HTML content using HtmlParser
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);

        // Format the HTML using AngleSharp’s HtmlFormatter
        var prettyHtml = document.ToHtml();
    }
}

Imports AngleSharp.Html.Parser
Imports System

Friend Class Program
	Shared Sub Main()
		Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>"

		' Parse the HTML content using HtmlParser
		Dim parser = New HtmlParser()
		Dim document = parser.ParseDocument(htmlContent)

		' Format the HTML using AngleSharp's HtmlFormatter
		Dim prettyHtml = document.ToHtml()
	End Sub
End Class

Imports AngleSharp.Html.Parser
Imports System

Friend Class Program
	Shared Sub Main()
		Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>"

		' Parse the HTML content using HtmlParser
		Dim parser = New HtmlParser()
		Dim document = parser.ParseDocument(htmlContent)

		' Format the HTML using AngleSharp's HtmlFormatter
		Dim prettyHtml = document.ToHtml()
	End Sub
End Class

HTML Output

HTML Prettifier (How it Works for Developers): Figure 5

Online HTML Beautifier (BeautifyTools)

HTML Prettifier (How it Works for Developers): Figure 6

BeautifyTools.com provides an easy-to-use online HTML formatter that allows you to format and prettify messy HTML code. This is useful if you want a quick and free way to clean up your HTML without installing any libraries or writing code.

How to Use the Online HTML Beautifier

Go to the Website

Open BeautifyTools.com HTML Beautifier in your web browser.
Paste Your HTML

Copy your raw or minified HTML and paste it into the input box.
Adjust the Settings (Optional)
- Choose the indentation level (Spaces: 2, 4, etc.).
- Enable/disable line breaks and formatting options.
Click "Beautify HTML"

The tool will process your HTML and display the prettified result in the output box.
Copy the Formatted HTML

Click "Copy to Clipboard" or manually copy the formatted HTML for use in your project.

HTML Prettifier (How it Works for Developers): Figure 7

Pros & Cons of Using an Online Beautifier

HTML Prettifier (How it Works for Developers): Figure 8

Pros & Cons of Using a Code-Based HTML Prettifier

HTML Prettifier (How it Works for Developers): Figure 9

Converting Prettified HTML to PDF with IronPDF

Once we have prettified our HTML, we can use IronPDF to convert it into a high-quality PDF. Here's a simple example using AngleSharp:

using AngleSharp.Html.Parser;
using System.IO;
using IronPdf;
using System;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This was formatted using AngleSharp.</p><p>Then it was converted using IronPDF.</p></body></html>";

        // Parse the HTML content using HtmlParser
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);

        // Format the HTML using PrettyMarkupFormatter
        using (var writer = new StringWriter())
        {
            document.ToHtml(writer, new PrettyMarkupFormatter()); // Format the HTML
            var prettyHtml = writer.ToString();
            
            // Save the formatted HTML to a file
            string outputPath = "formatted.html";
            File.WriteAllText(outputPath, prettyHtml);
            Console.WriteLine(prettyHtml);
        }

        // Convert the formatted HTML to PDF using IronPdf
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlFileAsPdf("formatted.html");
        pdf.SaveAs("output.pdf");
    }
}

using AngleSharp.Html.Parser;
using System.IO;
using IronPdf;
using System;

class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This was formatted using AngleSharp.</p><p>Then it was converted using IronPDF.</p></body></html>";

        // Parse the HTML content using HtmlParser
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);

        // Format the HTML using PrettyMarkupFormatter
        using (var writer = new StringWriter())
        {
            document.ToHtml(writer, new PrettyMarkupFormatter()); // Format the HTML
            var prettyHtml = writer.ToString();
            
            // Save the formatted HTML to a file
            string outputPath = "formatted.html";
            File.WriteAllText(outputPath, prettyHtml);
            Console.WriteLine(prettyHtml);
        }

        // Convert the formatted HTML to PDF using IronPdf
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderHtmlFileAsPdf("formatted.html");
        pdf.SaveAs("output.pdf");
    }
}

Imports AngleSharp.Html.Parser
Imports System.IO
Imports IronPdf
Imports System

Module Program
    Sub Main()
        Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This was formatted using AngleSharp.</p><p>Then it was converted using IronPDF.</p></body></html>"

        ' Parse the HTML content using HtmlParser
        Dim parser = New HtmlParser()
        Dim document = parser.ParseDocument(htmlContent)

        ' Format the HTML using PrettyMarkupFormatter
        Using writer As New StringWriter()
            document.ToHtml(writer, New PrettyMarkupFormatter()) ' Format the HTML
            Dim prettyHtml = writer.ToString()

            ' Save the formatted HTML to a file
            Dim outputPath As String = "formatted.html"
            File.WriteAllText(outputPath, prettyHtml)
            Console.WriteLine(prettyHtml)
        End Using

        ' Convert the formatted HTML to PDF using IronPdf
        Dim renderer = New ChromePdfRenderer()
        Dim pdf = renderer.RenderHtmlFileAsPdf("formatted.html")
        pdf.SaveAs("output.pdf")
    End Sub
End Module

Imports AngleSharp.Html.Parser
Imports System.IO
Imports IronPdf
Imports System

Module Program
    Sub Main()
        Dim htmlContent As String = "<html><body><h1>Hello World!</h1><p>This was formatted using AngleSharp.</p><p>Then it was converted using IronPDF.</p></body></html>"

        ' Parse the HTML content using HtmlParser
        Dim parser = New HtmlParser()
        Dim document = parser.ParseDocument(htmlContent)

        ' Format the HTML using PrettyMarkupFormatter
        Using writer As New StringWriter()
            document.ToHtml(writer, New PrettyMarkupFormatter()) ' Format the HTML
            Dim prettyHtml = writer.ToString()

            ' Save the formatted HTML to a file
            Dim outputPath As String = "formatted.html"
            File.WriteAllText(outputPath, prettyHtml)
            Console.WriteLine(prettyHtml)
        End Using

        ' Convert the formatted HTML to PDF using IronPdf
        Dim renderer = New ChromePdfRenderer()
        Dim pdf = renderer.RenderHtmlFileAsPdf("formatted.html")
        pdf.SaveAs("output.pdf")
    End Sub
End Module

Explanation

The above code demonstrates how to prettify HTML using AngleSharp and then convert it to a PDF using IronPDF. Here's how it works:

Define the Raw HTML Content:

The program starts with a simple HTML string containing a <h1> header and two paragraphs.
Parse the HTML with AngleSharp:

It initializes an HtmlParser instance and parses the raw HTML into a structured IDocument object.
Format the HTML using PrettyMarkupFormatter:
- The PrettyMarkupFormatter class is used to properly format and indent the HTML.
- A StringWriter is used to capture the formatted HTML as a string.
- After formatting, the formatted HTML is saved to a file named "formatted.html".
Convert the Formatted HTML to PDF using IronPDF:
- A ChromePdfRenderer instance is created to handle the conversion.
- The formatted HTML file is loaded and converted into a PdfDocument.
- The resulting PDF is saved as "output.pdf".
Final Output:
- The prettified HTML is displayed in the console.
- The program produces two output files:
  - formatted.html (a well-structured version of the HTML)
  - output.pdf (the final PDF document generated from the formatted HTML).

This approach ensures that the HTML is neatly structured before converting it to a PDF, which improves readability and avoids potential rendering issues in the PDF output.

Console Output

HTML Prettifier (How it Works for Developers): Figure 10

PDF Output

HTML Prettifier (How it Works for Developers): Figure 11

Why Use a Prettifier with IronPDF?

1. Better Readability and Debugging

Formatted HTML is easier to read, debug, and maintain. This is especially useful when working with dynamic content or large HTML templates.

2. Improved Styling Consistency

Prettified HTML maintains consistent spacing and structure, leading to a more predictable rendering in IronPDF.

3. Reduced Rendering Issues

Minified or unstructured HTML can sometimes cause unexpected issues in PDF generation. Prettification helps prevent missing elements or broken layouts.

4. Simplifies Automated Workflows

If your application programmatically generates PDFs, ensuring HTML is clean and well-formed before conversion improves stability and accuracy.

Conclusion

Using an HTML prettifier with IronPDF in .NET is a simple but effective way to enhance PDF conversion. By structuring your HTML correctly, you ensure better rendering, improved maintainability, and fewer debugging headaches.

With libraries like HtmlAgilityPack, AngleSharp, and HTML Beautifier, prettifying HTML before PDF generation becomes an effortless task. If you frequently work with HTML-to-PDF conversions, consider integrating an HTML prettifier into your workflow for optimal results.

Give it a try today and see how it enhances your IronPDF experience! Download the free trial and get started exploring all that IronPDF has to offer within your own projects.

Jacob Mellor

Chat with engineering team now

Chief Technology Officer

Jacob Mellor is Chief Technology Officer at Iron Software and a visionary engineer pioneering C# PDF technology. As the original developer behind Iron Software's core codebase, he has shaped the company's product architecture since its inception, transforming it alongside CEO Cameron Rimington into a 50+ person company serving NASA, Tesla, and global government agencies.

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