Google crawlers are programs that scan websites and index their content for Google’s search engine. They follow links from one web page to another and collect information about the pages they visit. Google uses different types of crawlers for different purposes, such as crawling images, videos, news, or ads. In this blog post, we will explain the main types of Google crawlers, how they work, and how they affect your SEO.

Googlebot: The Main Crawler for Google’s Search Products

Googlebot is the generic name for Google’s two types of web crawlers: Googlebot Desktop and Googlebot Smartphone. These crawlers simulate a user on a desktop or a mobile device, respectively, and crawl the web to build Google’s search indices. They also perform other product-specific crawls, such as for Google Discover or Google Assistant.

Googlebot always respects robots.txt rules, which are instructions that tell crawlers which pages or parts of a site they can or cannot access. You can use the User-agent: line in robots.txt to match the crawler type when writing crawl rules for your site. For example, User-agent: Googlebot means that the rule applies to both Googlebot Desktop and Googlebot Smartphone.

Googlebot crawls primarily from IP addresses in the United States, but it may also crawl from other countries if it detects that a site is blocking requests from the US. You can check the list of currently used IP address blocks used by Googlebot in JSON format.

Googlebot can crawl over HTTP/1.1 and, if supported by the site, HTTP/2. There is no ranking benefit based on which protocol version is used to crawl your site, but crawling over HTTP/2 may save computing resources for your site and Googlebot.

Googlebot can crawl the first 15MB of an HTML file or supported text-based file. Each resource referenced in the HTML, such as CSS and JavaScript, is fetched separately and has the same file size limit. The file size limit is applied on the uncompressed data.

Special-Case Crawlers: Crawlers That Perform Specific Functions

Besides Googlebot, there are other types of crawlers that perform specific functions for various products and services. Some of these crawlers may or may not respect robots.txt rules, depending on their purpose. Here are some examples of special-case crawlers:

  • AdsBot: Crawls pages to measure their quality and relevance for Google Ads.
  • Googlebot-Image: Crawls image bytes for Google Images and products dependent on images.
  • Googlebot-News: Crawls news articles for Google News and uses the same user agent strings as Googlebot.
  • Googlebot-Video: Crawls video bytes for Google Video and products dependent on videos.
  • Google Favicon: Fetches favicons (small icons that represent a website) for various products.
  • Google StoreBot: Crawls product data from online stores for various products.

You can find more information about these crawlers and how to specify them in robots.txt on this page.

How to Identify Google Crawlers

You can identify the type of Google crawler by looking at the user agent string in the request. The user agent string is a full description of the crawler that appears in the HTTP request and your weblogs. For example, this is the user agent string for Googlebot Smartphone:

Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/ W.X.Y.Z Mobile Safari/537.36 (compatible; Googlebot/2.1; +7)

However, be careful because the user agent string can be spoofed by malicious actors who want to trick you into thinking that their requests are from Google crawlers. To verify if a visitor is a genuine Google crawler, you can use reverse DNS lookup or DNS verification methods.

How to Optimize Your Site for Google Crawlers

Optimizing your site for Google crawlers means making sure that they can access, understand, and index your content properly. Here are some tips to help you optimize your site for Google crawlers:

  • Use descriptive, concise, and relevant anchor text (the visible text of a link) for your internal and external links.
  • Make your links crawlable by using HTML elements with href attributes that resolve into actual web addresses.
  • Use robots.txt to control which pages or parts of your site you want to allow or disallow for different types of crawlers.
  • Use sitemaps to tell Google about new or updated pages on your site.
  • Use structured data to provide additional information about your content to help Google understand it better.
  • Use canonical tags to tell Google which version of a page you want to index if you have duplicate or similar content on your site.
  • Use meta tags to provide information about your pages, such as the title, description, keywords, and language.
  • Use responsive web design to make your site adaptable to different screen sizes and devices.
  • Use HTTPS to secure your site and protect your users’ data.
  • Use speed optimization techniques to make your site load faster and improve user experience.

By following these tips, you can optimize your site for Google crawlers and improve your chances of ranking higher on Google’s search results. If you want to learn more about how Google crawlers work and how to monitor their activity on your site, you can use tools such as Google Search Console, Google Analytics, and Googlebot Simulator. These tools can help you identify and fix any issues that may affect your site’s performance and visibility on Google. Happy crawling!

Krishnaprasath Krishnamoorthy

Meet Krishnaprasath Krishnamoorthy, an SEO specialist with a passion for helping businesses improve their online visibility and reach.  From Technical, on-page, off-page, and Local SEO optimization to link building and beyond, I have expertise in all areas of SEO and I’m dedicated to providing actionable advice and results-driven strategies to help businesses achieve their goals. WhatsApp or call me on +94 775 696 867