How To Replace Html Content In C#

In this blog post, we will learn how to replace HTML content in C#. This can be particularly useful when you need to manipulate HTML files or web content programmatically for applications like web scraping or HTML templating. We will discuss two different methods to achieve this: using simple string manipulation and using the powerful HTML Agility Pack library.

Method 1: Using String Manipulation

The simplest way to replace HTML content in C# is by using basic string manipulation methods like Replace(). Let’s assume we have an HTML string as shown below:

string htmlContent = "<div><h1>Hello World</h1></div>";

Now, let’s say we want to replace the text “Hello World” with “Welcome to C#!”. We can accomplish this using the following code:

string newHtmlContent = htmlContent.Replace("Hello World", "Welcome to C#!");

This method works well for simple replacements, but it is not suitable for complex HTML manipulation, as it does not take into account the structure of the HTML document. For more advanced scenarios, we can use the HTML Agility Pack library.

Method 2: Using HTML Agility Pack

HTML Agility Pack is a versatile and powerful .NET library to parse and manipulate HTML documents. You can install it via NuGet by running the following command:

Install-Package HtmlAgilityPack

Once you have installed the library, let’s see how to replace content using HTML Agility Pack. In this example, we will replace the contents of an <h1> tag with a new value.

using System;
using HtmlAgilityPack;

class Program
static void Main()
string htmlContent = “

Hello World


HtmlDocument htmlDoc = new HtmlDocument();

HtmlNode h1Node = htmlDoc.DocumentNode.SelectSingleNode(“//h1”);
if (h1Node != null)
h1Node.InnerHtml = “Welcome to C#!”;

string newHtmlContent = htmlDoc.DocumentNode.OuterHtml;

In this code snippet, we first load the HTML content into an HtmlDocument object. We then use the SelectSingleNode() method to find the <h1> node in the HTML document. Once we have the <h1> node, we can easily replace its contents by modifying the InnerHtml property.

The output of this code will be: <div><h1>Welcome to C#!</h1></div>


In this post, we have learned two different methods to replace HTML content in C# – using simple string manipulation and the HTML Agility Pack library. While the string manipulation method is suitable for simple replacements, the HTML Agility Pack provides a more powerful and flexible solution for advanced HTML manipulation tasks.