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Google's Mobile-First Index: Is your website ready?

Mobile First Index

Google Rolls out Mobile-First Index

With over 50% of all search traffic now coming from mobile devices, Google has set out to continually make the web more mobile-friendly. In recent years they have introduced the Mobile-Friendly update, Accelerated Mobile Pages, the Intrusive Interstitial penalty, and on 4 November 2016 they announced that they will be experimenting with a new mobile-first index.

After a year and a half of experimenting, the mobile-first index is now being rolled out and webmasters have reported receiving notifications in Search Console stating their websites have been migrated to the mobile-first index.

What is Mobile-First Indexing?

Google will index and rank your website based on the mobile-friendly version of your site, even for search results shown to desktop users. Historically, the crawling, indexing, and ranking process has been based on the desktop version of your website, which can potentially cause a negative experience for mobile users when your website offers a different experience on mobile than on a desktop, for example, users might not be able to access certain pages or content on mobile.

With mobile-first indexing, Googlebot, Google’s main crawler that is used to discover and scan websites, will primarily crawl pages with the smartphone agent. Your website will then be indexed and ranked based on the mobile version of the page.

Google will continue to only have one index, and this will increasingly be based on mobile content rather than desktop content. There won’t be a separate index for desktop users, and if your website is desktop-only, then you can still be included in the mobile-first index. However, if you don’t offer a mobile-friendly experience, your rankings could be negatively impacted, and if your competitors offer a better mobile experience, they could potentially rank above you even for searchers on a desktop.

Is this different to the Mobile-Friendly update?

Yes. In April 2015, the Mobile-Friendly algorithm was released and was designed to give mobile-friendly pages a boost in mobile search results only and was not intended to have an effect on desktop search results. This was updated again in May 2016. Unlike the Mobile-Friendly update, the mobile-first index will base both mobile and desktop search results on the mobile-friendly version of your website.

The mobile-first index also goes further than simply having a responsive website, it will be crawling, indexing, and ranking websites based on the content and mark-up that is served on mobile devices in order to better help mobile users find what they’re looking for. So, while your website may be mobile-friendly, if it does not offer the same primary content as on desktop or effectively answer a user’s search query, then your performance in the SERPs may be negatively impacted.

Is your site ready?

This depends on several factors and how you deliver your mobile website. There tend to be three ways to deliver a mobile experience:

  1. Responsive design – If your website is responsive then your HTML mark-up should remain the same for mobile and desktop users, and generally your website will be ready for the mobile-first index. 
  2. Dynamic Serving – Dynamic serving allows you to serve different code on the same URL depending on the device that is being used. 
  3. Separate mobile URL – This is also known as an m-dot website. With this approach, a website will serve different code to mobile users and be on a different URL, for example, the desktop URL might be, and the mobile URL might be

If your website is responsive, then you should generally be ready for the mobile-fist index. However, it is still important to check certain technical SEO aspects, such as mobile page speed, and review the general optimisation of your website. We would also recommend manually reviewing your website on a mobile device to better understand the user experience and identify any errors that might go amiss in a standard crawl. We have seen an example of a website where the links have switched to a different URL when the page was viewed on mobile compared to desktop. Both links were in the HTML mark-up across all devices, but the one that was available to the user was based on their screen size, and this lead to mobile users going to the wrong page.

If you offer dynamic serving or serve your mobile site on a separate URL, then you will likely have more work to do to ensure your website is ready for the mobile-first index.

Google’s best practices to follow:

  • Meta data: Ensure that your page titles and meta descriptions are the same on both versions of your site
  • Structured data: Include the same structured data on mobile as on desktop, ensuring the mobile structured data contains the mobile URL and the desktop structured data contains the desktop URL.
  • Hreflang: If you have hreflang URLs implemented, ensure that these are correctly set up and that the mobile hreflang URL points to the mobile URL, and the desktop hreflang URL points to the desktop URL
  • Content: Ensure your primary content on mobile is equivalent to that on desktop, this includes text, images, and video. Please note that content which is collapsed or hidden in tabs will be treated the same as visible content.
  • Search console: If you have a separate mobile site, make sure that both your desktop and mobile sites are verified in Search Console.
  • Crawl rate: When your site is switched to mobile-first indexing, Google may potentially increase the rate at which it crawls your site. You need to ensure your servers can handle an increased crawl rate without it slowing your site down.
  • Robots.txt: If you have a separate mobile site, you might have a different robots.txt file for that site. You should ensure that your robots.txt directive works as intended for both versions of your site, in most cases, these should be the same for both mobile and desktop, and ensure your mobile version is accessible to Googlebot using the robots.txt testing tool.

Additional factors:

  • Page Speed: In July 2018, there will be a Speed Update that will be using page speed as a ranking signal for mobile searches. You should review and optimise your mobile page speed and load time where possible, you can check your mobile page speed here and here and identify areas to optimise for speed.
  • Internal links: Internal links help Googlebot and other search engines crawl your website and find internal pages. It is important that your mobile site’s internal link structure is set up in the same way as desktop. There are several tools that you can use to review your internal link structure, such as Screaming Frog. 
  • Redirects: Your site will likely have many redirects set up to send users and search engines to the correct URL when a page is changed or removed. Check your redirects are set up correctly on your mobile site as well as your desktop site.
  • CTR: Use Search Console to review and compare CTR on desktop and mobile. If there is a significant difference on mobile, look at how you can improve this and review how your page titles and meta descriptions appear in the mobile search results.
  • Intrusive interstitials: Google have already stated that they may not rank a website as highly if they have intrusive interstitials on their mobile website. Where possible, keep these to a minimum and follow Google’s guidelines on how to present an interstitial on mobile.
  • Social metadata: Include social metadata, such as OpenGraph tags and Twitter cards on your mobile version as well as your desktop version.

What if you only have a desktop website?

If your website is desktop only, then your site can still be crawled and indexed, however, you may be at a disadvantage and your rankings might be negatively impacted, particularly if there is another site that offers a more mobile-friendly experience.

When will your site move to the mobile-first index?

On March 26, 2018, Google announced that its mobile-first index was beginning to roll out for websites that follow the best practices for mobile-first indexing. If your website has not yet been migrated to the mobile-first index, Google have said that you don’t need to panic, stating:

Mobile-first indexing is about how we gather content, not about how content is ranked. Content gathered by mobile-first indexing has no ranking advantage over mobile content that’s not yet gathered this way or desktop content. Moreover, if you only have desktop content, you will continue to be represented in our index.

When your site is migrated to the mobile-first index, you should receive a notification in Google Search Console. Google also said you “will see an increased crawl rate from the Smartphone Googlebot. Additionally, Google will show the mobile eversion of pages in Search results and Google cached pages.”.