Home > Uncategorized > #OpenSource web crawler in C# based on #HTMLAgilityPack

#OpenSource web crawler in C# based on #HTMLAgilityPack



Here’s the Repo; https://github.com/infiniteloopltd/WebCrawler/

A Web Spider based using HTMLAgilityPack. This library will follow links within webpages in order to find more webpages, it works asynchronously, and will fire events every time a new page is encountered.

A few caveats, is that it’s single-threaded, so, it’s going to be rather slow. It holds it’s queue in memory, so it’s going to be a memory hog on really large websites. It also doesn’t obey Robots.txt.

Please feel free to fork this library, and improve upon it!

Sample Usage

  Spider.OnQueueUpdate = q =>
      Console.WriteLine("Crawler Queue updated : " + q);
      if (q == 0)
          // when this reaches 0, then the crawl is complete
          Console.WriteLine("Crawl Complete");
  Spider.OnVisitedPage = (webpage,content) =>
      Console.WriteLine("Crawler visited : " + webpage.Url);
  Spider.OnCrawlError = (webpage, ex) =>
      Console.WriteLine("Crawler hit error at : " + webpage.Url);
  Spider.StartPage = new Uri("https://www.cloudansweringmachine.com/");
  Spider.Scope = "https://www.cloudansweringmachine.com/"; // Don't leave this domain.
  Console.WriteLine("Crawl stated, press enter to stop.");



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