Parsing HTML in C# (.NET): Overview of Libraries and Code Examples

Parsing HTML in C# (.NET): From Simple to Complex

HTML parsing is one of the key tasks when developing web scrapers, content analyzers, and automation tools. In the C# (.NET) ecosystem, there are several mature libraries that allow you to efficiently extract data from HTML documents, even if the markup is invalid. In this article, we will look at three of the most popular tools: HtmlAgilityPack, AngleSharp, and CsQuery, and also analyze practical examples of their use.

1. HtmlAgilityPack — The Classic Choice

HtmlAgilityPack (HAP) is the most common library for parsing HTML in C#. It supports XPath and LINQ, making it ideal for working with hierarchical structures. HAP automatically corrects invalid HTML markup, which is especially useful when parsing "raw" pages.

Installation via NuGet:

Install-Package HtmlAgilityPack

Example: Extracting all links from a page

using HtmlAgilityPack;

string url = "https://example.com";var web = new HtmlWeb();var doc = web.Load(url);

var links = doc.DocumentNode.SelectNodes("//a[@href]");if (links != null){    foreach (var link in links)    {        string href = link.GetAttributeValue("href", "");        string text = link.InnerText.Trim();        Console.WriteLine($"{text}: {href}");    }}

Example: Extracting data from a table

var tableRows = doc.DocumentNode.SelectNodes("//table[@id='data-table']//tr");foreach (var row in tableRows){    var cells = row.SelectNodes("td");    if (cells != null)    {        var rowData = cells.Select(c => c.InnerText.Trim()).ToList();        Console.WriteLine(string.Join(" | ", rowData));    }}

2. AngleSharp — A Modern Alternative

AngleSharp is a more modern library, entirely written in C# and compliant with W3C specifications. It supports CSS selectors, making it convenient for those accustomed to jQuery-like syntax. AngleSharp can also work with DOM, SVG, and MathML.

Installation via NuGet:

Install-Package AngleSharp

Example: Parsing using CSS selectors

using AngleSharp;using AngleSharp.Dom;

var config = Configuration.Default.WithDefaultLoader();var context = BrowsingContext.New(config);var document = await context.OpenAsync("https://example.com");

// Get all elements with the class "product"var products = document.QuerySelectorAll(".product");foreach (var product in products){    var name = product.QuerySelector(".product-name")?.TextContent.Trim();    var price = product.QuerySelector(".product-price")?.TextContent.Trim();    Console.WriteLine($"{name}: {price}");}

Example: Extracting JSON from a script

var scripts = document.QuerySelectorAll("script[type='application/ld+json']");foreach (var script in scripts){    var json = script.TextContent;    // Next, you can deserialize the JSON using System.Text.Json    Console.WriteLine(json);}

3. CsQuery — jQuery-like Syntax

CsQuery is a port of jQuery for C# that provides a familiar API for working with the DOM. It is especially convenient for those migrating from JavaScript to C#. However, it is worth noting that the project is updated less frequently than AngleSharp and may not support the latest versions of .NET.

Installation via NuGet:

Install-Package CsQuery

Example: Extracting text from elements

using CsQuery;

string html = "<div class='content'><p>Hello, world!</p></div>";var dom = CQ.Create(html);

var text = dom[".content