How Web Crawlers Work And Their Pros And Cons

If you are somehow into the IT business or owning websites, then this web crawler is one of the generic terms you have heard. There are plenty of reasons we are using web crawlers and analyze data.

For example, the search engine uses the crawler to crawl the newly added websites on the web or the changes made in the existing website. Search engines crawl all these and then list those on their search engine result page for the user interaction.How Web Crawlers Work

Similarly, companies use the web crawler to get some data about their business or to analyze the competitors’ business to take certain action. All though you can create your own web crawler if you are a technical person or you can hire the specialist companies like scraping web crawler Toronto to get your work done.

Techopedia gave a definition to web crawler and as per them,

“It is an internet bot which helps in web indexing. They crawl one page of the website at a time until all pages have been indexed. It also collects the links associated with those websites which can be analyzed later on to validate the HTML and CSS tags as well.”

What a web crawler collects?

Here is some general information those a web crawler collects-

  • URL of the website
  • Meta tag information
  • Web page content
  • Links in the webpage
  • Destinations leading from those links,
  • Web page title and similar multiple other information can be crawled

Also, a good web crawler usually eliminates the duplicate stuff that means to say, if something has been already downloaded, they skip it and follows the next in the line. Using this information, you can also analyze SEO status of your website and can work on the on-page SEO optimization stuff.

How does web crawler work?

Here is a typical image showing the working of the web crawler-Web Crawlers Work

The generated files from these crawlers will be usually the XML files which later need to be parsed if you are looking for the structured data out of it.

Usually, when a web crawler is reaching to your page, it will download the content of the page to the database. Once the requested page has been fetched, the texts of your page will be loaded into the search engine’s index. In this complete process, below are the three steps usually involved-

  • Search engine bots start by crawling the pages of your site
  • It will index the content and links of your page and will visit the links found on your page to verify if those really exists or it’s dead
  • When the bot doesn’t find any page, it will delete the page from search engine index and you will get 404 error message.

Usually, a good bot will revisit the pages which were not found in the first crawl to confirm if those really doesn’t exist or it is due to the intermittent issue.

Pros and cons of web crawler

Here are some of the leading pros and cons of using the web crawlers-


  • You get to gather the data you want for your further analysis
  • If your site is included in some index or search engine, you will get additional and organic traffic as well


  • Your traffic will get increased and if you are running on low bandwidth and space, this may cause an issue with your website.


These were all about the web crawler which you can use. If you are looking for the data for any website, web crawlers can be a great help. But make sure you are using only good crawlers else there is a chance of IP address blacklist as well.