How to Crawl Website with .NET and C#

Want to crawl websites efficiently using .NET and C#? Here's everything you need to know to get started, from choosing the right tools to writing your first crawler. Whether you're extracting data from static pages or handling JavaScript-heavy sites, this guide covers:

• Top Tools: Use open-source frameworks like Abot for multithreaded crawling or SkyScraper for handling dynamic content with async/await.
• Code Examples: Learn how to set up and configure crawlers for both frameworks.
• Simpler Options: Explore WebCrawlerAPI for scalable, hassle-free crawling with features like proxy rotation and JavaScript rendering.

Quick Comparison

In short: Use Abot for flexibility, SkyScraper for modern web content, or WebCrawlerAPI for simplicity and scale. Ready to dive in? Let’s explore these tools step-by-step!

Using Open-Source C# and .NET Frameworks for Web Crawling

Now that we've looked at why C# and .NET are great for web crawling, let's dive into two open-source frameworks that make the process easier: Abot and SkyScraper.

Abot Framework Overview

Abot is designed for high-performance, multithreaded crawling and offers features like configurable crawl depth, an event-driven structure, and respect for robots.txt and crawl delays.

Setting Up and Configuring Abot

Here's an example of how to use Abot for crawling:

using Abot;
using Abot.Poco;

var crawler = new PoliteWebCrawler();
var config = new CrawlConfiguration
{
    MaxPagesToCrawl = 100,
    MaxLinksPerPage = 50,
    StartUrl = "https://example.com"
};

crawler.CrawlCompleted += (sender, e) =>
{
    foreach (var page in e.CrawledPages)
    {
        var data = page.HtmlDocument.DocumentNode
            .SelectSingleNode("//div[@class='data']").InnerText;
        Console.WriteLine(data);
    }
};

crawler.Crawl(config);

This script sets up a crawler with limits on pages (100) and links per page (50). The CrawlCompleted event processes each page, extracting content from elements with the data class using SelectSingleNode.

SkyScraper Framework Overview

SkyScraper leverages C#'s async/await features and Reactive Extensions for efficient handling of modern web content, including AJAX-loaded pages.

Setting Up and Using SkyScraper

Here's how to get started with SkyScraper:

using SkyScraper;
using SkyScraper.Poco;

var crawler = new WebCrawler();
var config = new CrawlConfiguration
{
    StartUrl = "https://example.com/dynamic-page",
    MaxDepth = 3,
    DelayBetweenRequests = TimeSpan.FromSeconds(1)
};

await crawler.CrawlAsync(config);  // Start the crawl asynchronously

foreach (var page in crawler.CrawledPages)  // Process each crawled page
{
    var data = page.HtmlDocument.DocumentNode
        .SelectSingleNode("//div[@class='data']").InnerText;
    Console.WriteLine(data);
}

This example sets a starting URL, limits the crawl depth to 3 levels, and adds a 1-second delay between requests. The CrawlAsync method handles the crawling, while the loop extracts and processes page data.

The right framework depends on your project's needs. Both Abot and SkyScraper are excellent for .NET-based web crawling, but simpler projects might benefit from API-based tools like WebCrawlerAPI, which we'll discuss next.

Alternative: Using WebCrawlerAPI for Crawling

If open-source frameworks like Abot and SkyScraper feel too complex or don't meet your needs, WebCrawlerAPI is a simpler and scalable option for web crawling in C# applications.

Why Choose WebCrawlerAPI?

WebCrawlerAPI stands out by offering features that streamline modern web crawling tasks. Here's a quick breakdown:

How to Integrate WebCrawlerAPI with C#

Setting up WebCrawlerAPI is straightforward, especially compared to traditional frameworks. Here's a sample implementation.

Installation

dotnet add package WebCrawlerApi

Basic example

using WebCrawlerApi;
using WebCrawlerApi.Models;

// Initialize the client
var crawler = new WebCrawlerApiClient("YOUR_API_KEY");

// Synchronous crawling (blocks until completion)
var job = await crawler.CrawlAndWaitAsync(
    url: "https://example.com",
    scrapeType: "markdown",
    itemsLimit: 10,
);

Console.WriteLine($"Job completed with status: {job.Status}");
// Access job items and their content
foreach (var item in job.JobItems)
{
    var content = await item.GetContentAsync();
    if (content != null)
    {
        Console.WriteLine($"Content length: {content.Length}");
        Console.WriteLine($"Content preview: {content[..Math.Min(200, content.Length)]}...");
    }

}

Starting at just $20 per month for 10,000 pages, WebCrawlerAPI offers a budget-friendly solution that balances simplicity with enterprise-grade features. It’s an excellent choice for handling modern, complex, or large-scale web crawling projects.

Summary and Key Takeaways

Different tools suit different needs, and understanding their strengths can help you make the right choice.

Abot Framework is perfect for developers who need to fine-tune their crawling processes, while WebCrawlerAPI is a great option for enterprise-level projects, offering plans starting at $20/month for up to 10,000 pages. Its automated setup and ability to handle complex web technologies make it a dependable choice.

Here’s a quick breakdown of what each tool offers:

• Abot Framework:
  • Full control over the crawling process
  • Seamless integration with existing systems
  • Budget-friendly for smaller-scale projects
• WebCrawlerAPI:
  • Easy setup with minimal effort
  • Handles modern web technologies effectively
  • Scales effortlessly for large-volume crawling tasks

Pick Abot if you need customization and control, or go with WebCrawlerAPI for ease of use and scalability. Both tools bring unique strengths to the table.

FAQs

What is the best web scraping library for C#?

Picking the right library can make web scraping much smoother. Here's a quick comparison of popular options and their strengths:

When deciding on a library, think about these factors:

• Project complexity: For straightforward tasks, HtmlAgilityPack might be enough. For more advanced needs, combining tools could work better.
• Performance demands: HttpClient is ideal for handling multiple requests efficiently with its asynchronous features.
• Long-term support: Check for active community involvement and comprehensive documentation.

If you're working on a large-scale project, WebCrawlerAPI is worth exploring for its built-in anti-scraping features, as mentioned earlier.