Web Crawler 101: The Ultimate Web Crawler Guide

1. What is a Web Crawler?

Web Crawler is known in the SEO industry by many names. It has been called a web spider, the automatic indexer, and web root. It indexes the websites that have allowed crawling and indexing of their websites. Web crawler collects script data on that website and send it to search engines. Google categorises this data, ensuring that users get accurate search results.

Web crawler updates web indices by adding information about other websites’ content. It copies the data about websites’ visited pages so that search engines can process it. The search engine indexes the downloaded pages to facilitate quick search results. Furthermore, it also takes on tasks such as validating the site’s HTML code and checking its links.

1.1 Web Crawlers Examples

Listed below are some of the top crawler-based search engines, along with their respective Web crawling bots.

• Googlebot (Google)
• Amazonbot (Amazon)
• Bingbot (Bing)
• Baiduspider (Baidu)
• DuckDuckBot (DuckDuckGo)
• Yahoo! Slurp (Yahoo)

1.2 Web Crawler is not Web Scraper!

Web scraping is extracting data from websites. Once collected, the data is exported into a format better understandable to the user. A simple example would be extracting a product list and its prices from online retail software such as Flipkart and Amazon and exporting it into a spreadsheet program such as Microsoft Excel or LibreOffice’s calc.

Instead of manually exporting the data, users prefer to utilize the web scraper tools that perform the extraction for them. These web scrapers are available in various formats. It can be installed on your computer or used online as a browser extension.

Unlike web crawlers, web scraping has nothing to do with SEO. It is basically a data extraction process. These can be used for scraping stock prices, sports stats, store locators, etc.

Further reading: 110+ Actionable SEO Steps To Success

2. How Does Web Crawler Work?

It is a programming script developed by vendors such as Google. The purpose of these crawlers is to collect data and send it to Google. The name crawler comes from the nature of this programming script.

Suppose the web spider is crawling a website, and it comes across a link. In such instances,

• The web spider will sort of clone itself.
• The clone will be sent along to collect data and analyse the linked web page, while the original spider will continue on the same website, repeating the process whenever necessary.

This creates a virtual web, aptly describing the workings of a web crawler.

It conducts an inspection of sorts, collects the data, and forwards it to Google. Google top results include the best results from all this collected data. Think of it as a shelf. On the top section of these shelves, Google puts the best books, while the bottom ones are reserved for less relevant results. In order to rank your website on Google, your content has to answer the questions people have. When you satisfy a user, they are bound to return to the website for more information.

Let’s summarise it in simple steps:

• Crawling Process: Collects data from websites that allow crawling and indexing. Once collected, the data is forwarded to Google or other search engines, depending on the crawler vendor.
• Indexing Process: Google then shelves the data based upon its relevance and importance to users. These URLs and other site data is processed and stored in a Google database.
• Ranking Process: When a user enters a query on Google, the search engine presents the users with results from this stored database, sharing results relevant to their keyword. Relevance is a key factor in the ranking of a website on a search engine.

3. Why do we need web crawlers?

Web crawlers are not web scrapers! Web crawling tools incorporate web crawler bots. These tools analyse and audit one or many websites providing a detailed analysis on those websites. We have listed a few things that effective web-crawling tools will help you with:

• Find Broken Links: The Internet is an ever-growing, changing organism. It is constantly developing with new sections emerging every day while some parts vanish. Such vanishing web pages can leave behind broken links. These broken links can spoil the user experience. Once the crawler finds the broken links, you can fix that error.
• Find Server Errors: Quite like broken links, Server errors are also bad for business. They can stop users from accessing your website, which could push them towards your competitors. With website crawlers constant monitoring, you can stay ahead of these errors and fix them any time one occurs.
• Multiple-Domain Monitoring: With the right web crawling tool, you can monitor multiple domains. It keeps all your websites running smoothly. Monitoring websites allows you to respond quickly to errors and improve your websites’ health and traffic. It also positively affects revenue generation.
• Analyses Metadata and Page titles: As we have seen, metadata is significant to the web crawling process. The crawlers collect this data and help Google’s algorithm understand the content of your website. It helps Google provide valuable and relevant results to the users. Web-crawling tools can help you analyse metadata and page tiles effectively and suggest changes if necessary.

Read: Experts Share Best WordPress SEO Tips to Boost Rankings

4. How to Block Web Crawlers?

Digital Marketing enterprises have to always remain on top of the trends, designing landing pages essential for marketing or branding campaigns. These campaign web pages are an example of web pages that don’t have to be crawled.

If you allow the web crawlers to crawl these pages, they can gain access to your campaign strategies. So it is necessary to block crawlers from pages that contain sensitive information. Blocking the web crawlers on some pages will improve the overall web crawling experience by blocking irrelevant and redundant pages.

The no index tag sends web crawlers the message that they are not to include the page in search results. To simply exclude your page from search results, do the following:

• Step 1: Go to the head section of your website’s code/script and add the following:
meta name=”robots” content=”noindex,follow”
• Step 2: Now with the Disallow Directive, you can tell the search engines to not crawl your web page. You can block the web crawler for a particular URL by adding the following code into your website’s robots.txt file.
Disallow: /webpage UR/
• Step 3: If you want the pages to be neither crawled nor indexed, add the following to your Robot.txt file.
Disallow: / web page URL/
Noindex: / web page URL/

For more information on how to effectively block web crawlers, refer to the handy Web crawler blocking guide.

5. Industry’s Top 4 Web Crawling Tools

We are going to list some of the industry’s top web crawling tools preferred by SEO experts.

1. Screaming Frog

Highlights

• Screaming Frog is a dedicated web crawling tool with free and paid features
• 500 URLs crawled with Free version and unlimited crawls with a paid version
• Crawl comparison with the paid version
• With the paid version, Save crawls and Re-upload them
• Discover exact duplicate pages
• Find broken links, redirects, and errors.

2. SEMRush

Highlights

• SEMrush is the complete SEO tool. The free version allows you to monitor one website with only 10 reports per day.
• With a paid account, you can have access to at least 3,000 searches daily.
• The website crawler effectively analyses pages and website structure, zoning on the technical SEO issues that need to be fixed.
• SEMrush will test your website’s metadata, duplicate content, and page responses.
• Its user-friendly dashboard allows you to easily handle the website providing a hassle-free experience.

3. Sitechecker

Highlights

• With the PRO account, users can track as many as 3000 backlinks.
• All pricing plans include unlimited site audit reports, unlimited on-page checker, local rank tracking, and mobile rank tracking.
• It scans both internal and external links on your website.
• With the Sitechecker PRO version, you can check indexing issues on the website landing pages.
• Google Search Console Integration.
• Unlimited traffic checker with all paid plans.

4. Visualping

Highlights

• Visualping is one of the best free web crawling and monitoring tool
• A user-friendly interface allows you to easily get started
• Automatic monitoring of single or multiple web pages
• Allows you to track your competitor’s keywords
• It scans your website for text, code, or any visual changes
• It offers multiple notification options with email, Discord, Slack, or Teams