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HTML Prettifier (How it Works for Developers)

Name: IronPDF
Brand: Iron Software
Availability: InStock
Rating: 4.87 (307 reviews)

Chipego Kalinda

April 3, 2025

Introduction

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 a 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

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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

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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>";
        HtmlDocument doc = new HtmlDocument();
        doc.LoadHtml(htmlContent);
        // Prettify the HTML by saving it with indentation
        string prettyHtml = doc.DocumentNode.OuterHtml;
        // Saves the formatted HTML with the prettified indenting
        doc.Save("pretty.html");
    }
}

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>";
        HtmlDocument doc = new HtmlDocument();
        doc.LoadHtml(htmlContent);
        // Prettify the HTML by saving it with indentation
        string prettyHtml = doc.DocumentNode.OuterHtml;
        // Saves the formatted HTML with the prettified indenting
        doc.Save("pretty.html");
    }
}

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>"
		Dim doc As New HtmlDocument()
		doc.LoadHtml(htmlContent)
		' Prettify the HTML by saving it with indentation
		Dim prettyHtml As String = doc.DocumentNode.OuterHtml
		' Saves the formatted HTML with the prettified indenting
		doc.Save("pretty.html")
	End Sub
End Class

$vbLabelText $csharpLabel

Output HTML File

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Using AngleSharp as a HTML Prettifier

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

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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 AngleSharp.Dom;
using System;
class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";
        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 AngleSharp.Dom;
using System;
class Program
{
    static void Main()
    {
        string htmlContent = "<html><body><h1>Hello World!</h1><p>This is a test.</p></body></html>";
        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 AngleSharp.Dom
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>"
		Dim parser = New HtmlParser()
		Dim document = parser.ParseDocument(htmlContent)
		' Format the HTML using AngleSharp's HtmlFormatter
		Dim prettyHtml = document.ToHtml()
	End Sub
End Class

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HTML Output

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

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Online HTML Beautifier (BeautifyTools)

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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 Add from PixabayUpload

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Pros & Cons of Using an Online Beautifier

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Pros & Cons of Using a Code-Based HTML Prettifier

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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 AngleSharp.Dom;
using AngleSharp.Html;
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>";
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);
        // Format the HTML using AngleSharp’s HtmlFormatter
        using (var writer = new StringWriter())
        {
            document.ToHtml(writer, new PrettyMarkupFormatter());
            var prettyHtml = writer.ToString();
            document.Close();
            // 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
        ChromePdfRenderer renderer = new ChromePdfRenderer();
        PdfDocument pdf = renderer.RenderHtmlFileAsPdf("formatted.html");
        pdf.SaveAs("output.pdf");
    }
}

using AngleSharp.Html.Parser;
using AngleSharp.Dom;
using AngleSharp.Html;
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>";
        var parser = new HtmlParser();
        var document = parser.ParseDocument(htmlContent);
        // Format the HTML using AngleSharp’s HtmlFormatter
        using (var writer = new StringWriter())
        {
            document.ToHtml(writer, new PrettyMarkupFormatter());
            var prettyHtml = writer.ToString();
            document.Close();
            // 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
        ChromePdfRenderer renderer = new ChromePdfRenderer();
        PdfDocument pdf = renderer.RenderHtmlFileAsPdf("formatted.html");
        pdf.SaveAs("output.pdf");
    }
}

Imports AngleSharp.Html.Parser
Imports AngleSharp.Dom
Imports AngleSharp.Html
Friend Class Program
	Shared 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>"
		Dim parser = New HtmlParser()
		Dim document = parser.ParseDocument(htmlContent)
		' Format the HTML using AngleSharp's HtmlFormatter
		Using writer = New StringWriter()
			document.ToHtml(writer, New PrettyMarkupFormatter())
			Dim prettyHtml = writer.ToString()
			document.Close()
			' 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 As New ChromePdfRenderer()
		Dim pdf As PdfDocument = renderer.RenderHtmlFileAsPdf("formatted.html")
		pdf.SaveAs("output.pdf")
	End Sub
End Class

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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
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

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PDF Output

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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 start exploring all that IronPDF has to offer within your own projects.

Chipego Kalinda

Chat with engineering team now

Software Engineer

Chipego has a natural skill for listening that helps him to comprehend customer issues, and offer intelligent solutions. He joined the Iron Software team in 2023, after studying a Bachelor of Science in Information Technology. IronPDF and IronOCR are the two products Chipego has been focusing on, but his knowledge of all products is growing daily, as he finds new ways to support customers. He enjoys how collaborative life is at Iron Software, with team members from across the company bringing their varied experience to contribute to effective, innovative solutions. When Chipego is away from his desk, he can often be found enjoying a good book or playing football.

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