A Quick and Easy Guide to Mobile-first Indexing Author Marcin Gorczyca Read bio Signals of ChangeIn the first decade of the 21st century, the search world was easy. Every internet search was performed on a desktop device. The use of internet connections on mobile devices was limited to downloading funny wallpapers and polyphonic ringtones through paid SMS services, advertised at the back end of glossy magazines.With the introduction of smartphones and tablets, the mobile search market started to grow and after a few years it was clear that it was just a matter of time before it would overtake the desktop hegemony.Today we find ourselves in a world where most search queries are sent from mobile devices with screens vastly different in terms of size and proportion from desktop displays, inferior processing power, and often with slower internet connections.Web developers and search engines had to adapt to this change, and serve mobile users with mobile-friendly content, designed to fit onto a screen that you can carry in your pocket.But that’s not enough.There’s little reason (other than historical) to keep search algorithms desktop-oriented, and Google is making the switch to mobile-oriented algorithms right now. The first signal of the incoming Google Mobile-first indexing appeared around the end of 2016 in the form of an announcement. Recently, the topic was brought back by Google in December 2017 as a “last warning.” Then, at the end of March 2018, Google stated that D-day has come, and started rolling out the update.If it didn’t scare you enough then, surely it does now. For Everything to Stay the Same, Everything Must ChangeWhat is Mobile-first Indexing About?This change is about how Google perceives the web. Currently, Google discovers your content in the way it’s presented to desktop users. However, with the Mobile-first Index this will change, and Google will be looking primarily at your mobile site.From a technical point of view, the User Agent determines whether a server request will be treated like a desktop or mobile user. Currently, the most frequently used GoogleBot crawler is the desktop one. Here’s the User Agent:Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)It discovers new URLs by following links and parses the content it finds. It’s accompanied by specialized crawlers such as image-bot, ads-bot, or mobile-bot, which support the desktop crawler with parsing specific content. The data is then sent to the indexer, which ‘remembers’ what’s on a given page.After the update, Google will be more interested in your mobile pages, therefore you should expect to see more requests coming from the mobile GoogleBot. Here’s the User Agent:Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)Google promised to be cautious with rolling out the process of the update and they began switching to Mobile-first only for those sites which were ready. Nevertheless, I believe that the change is inevitable and will come to all websites sooner or later. Regardless of the update, the content parity audit described in this article is something you should include in your SEO strategy anyway.Is My Website in the Mobile-first Indexing? So, you’d like to know how to determine if your website has switched to the mobile-first index? Look for a message like this in your Google Search Console (GSC) account.If you don’t have your GSC account configured, you should definitely do it! It’s easy and very rewarding. But there are alternative methods. Check your server logs and look for requests from the mobile Googlebot. If the number of requests is higher than from the desktop crawler, you’ve probably been switched. If you cannot access the log files, you can use this php script instead.Who Should Worry about the Update?Websites with different mobile and desktop versions should worry about the update, mainly sites with separate mobile URLs. On the other side of the spectrum are websites with responsive design. Well-implemented responsive design guarantees content uniformity across all platforms. Here’s a great presentation that shows the impact of Mobile-first Index on different mobile implementations prepared by Google. Your main concerns should be: Is your content present on the mobile site?Is your website structure the same on mobile?Are your alternate/canonical tags implemented correctly (also on mobile)?Are the desktop/mobile redirects implemented correctly?So to recap: Is your mobile site following Google’s Best practices for mobile-first indexing?If you can answer these questions, that’s great! That means that you should possess the correct knowledge in order to make a judgement. If not, I’m going to emphasize the biggest risks related to this change. I’ll also show you how to perform the Content Parity Audit later in the article, which will help you spot the differences between your desktop and mobile site.What Will Change with the Mobile-first Index?The first big change, already confirmed by Googler John Mueller, is in regard to hidden content. On a desktop, when you have content hidden under a tab, it’s indexed differently and Google treats it as less important than plainly visible content. However, on mobile devices the smaller screen size forces developers to use these tabs in order to avoid flooding users with text, so Google will act accordingly and should accept such content with full value. Another one is the site structure. Mobile pages often have a limited amount of links in the navigation compared to their desktop equivalents. Some menus don’t go as deep, and some are simply cut in order to fit on a smaller screen. Along with changing the User Experience, this changes the PageRank flow on the site as well. If you don’t provide the same link structure on your mobile site as on your desktop site, you might see ranking changes.Audit the Mobile Version of Your WebsiteMake sure your SEO tags are implemented properly. Pay attention to the canonical tags, hreflang settings, meta tags, and structured data. It’s extremely important that Google can process the information contained within those data structures.Many developers focus on implementing structured data (e.g., json-ld, schema.org) only for desktop pages. But if you’re in a situation where your desktop and mobile sites are separate, you have to make sure that the Mobile Googlebot sees the structured data as well. Google recommends to keep it on both the desktop and mobile versions of the page. Separate URLs for Mobile SiteThis is a common implementation for mobile sites, so I’d like to elaborate a bit more on how to properly configure meta tags on these kind of sites, because they are often not very well optimised. The most common type of implementation is mobile subdomain, like m.example.com. Obligatory elements:rel=”canonical” link on every mobile page that points to the desktop equivalent of that page.rel=”alternate” link on every desktop page that points to the mobile equivalentThe URL pairs should be unique: this means that each mobile page should have exactly one canonical desktop version, which should also link to the mobile version with a single rel=”alternate” link.If you target multiple regions and/or languages, you should use the rel=”alternate” hreflang=”x” tags. For more general info on those tags visit Google support page. Here I’ll focus on how to deal with those tags on mobile subdomain pages. Let’s say, we’ve got a page available on 4 URLs: English desktop (example.com), English mobile (m.example.com), Polish desktop (example.pl), and Polish mobile (m.example.pl)Use hreflangs on the desktop versions of the page: example.com should contain a hreflang pointing to example.pl and vice-versa, the Polish page should point to example.com with a hreflang tag.Use hreflangs on the mobile versions of the page. m.example.com should contain a hrelfang pointing to mobile version of the Polish page: m.example.pl, and vice-versa, m.example.pl should point with a hreflang tag to m.example.com.Deal with Immediate Threats FirstThe very first threat that you should deal with is the risk of non-crawlability. It’s the most basic need for your website. Perform a Content Parity AuditIn order to ensure crawlability, you should, well, crawl your website as a mobile user in spider mode. Pretty much all modern crawlers have the possibility to change the user agent. Make sure to perform a crawl with a mobile user agent and compare it to a desktop-driven crawl.While you do the crawlability check, you should also do a content parity audit. Check the most basic parameters: number of pages, number of indexable pages, noindex tags, robots.txt settings, number of words on pages (note that changes in navigation and source code might perturb the last metric, treat it as a suggested measurement). Make sure that nothing blocks the mobile crawler from accessing your website. To set your crawler in mobile mode, you have to change the User Agent. Here’s a very quick tutorial on how to do this in Screaming Frog.You can also accomplish this with DeepCrawl. It offers a very user friendly way to perform the content parity audit. It allows to crawl mobile and desktop versions of a site with a single project. Afterward, you can compare the crucial metrics between both versions. There is also a very helpful crawl comparison tool in Sitebulb. You can perform one crawl as a desktop user, and another with a mobile user agent. The resulting comparison shows many useful metrics in a clear, user-friendly manner. Some of the metrics are shown on the screenshot below. Gather More Details About a Specific PageIf you spot any problems, Google Chrome inspect (Developer Tools) will be your best friend. It allows you to easily switch between mobile and desktop versions, and choose different User Agents.In that view look for differences between the mobile and desktop versions. Especially search for missing links and content.If that seems complicated, there is a very simple webpage tool that allows you to compare the number of outlinks on the desktop and mobile versions of a page. You can also compare the source codes of your desktop and mobile pages using a text-comparing tool, like for example Diff Checker. If you have a different HTML document for your mobile and desktop versions don’t expect the code to match exactly, but rather look for specific parts.Example Not to FollowA good example of a completely different linking structure on mobile and desktop versions of the site is Giphy: DesktopMobileEvery GIF that you can see on the mobile page contains a link. The structure on Mobile is much richer than on desktop. This might lead to a change in crawlability, PageRank flow, and ultimately rankings. That’s the resulting visibility drop.Pretty drastic, huh? Missing links are obviously not the only SEO problem that Giphy has. Here is the full Giphy visibility drop case study by Tomek Rudzki.Follow Google’s Mobile-friendly GuideIf you compete in the mobile world, you had to adjust your site to the Google mobile-friendly directives already, but if you don’t, it’s high time to verify your mobile site. In particular I’d like to emphasize the risk of using Interstitials. Google has always discouraged the use of full screen ads, but now with the Mobile-first index on the horizon, you risk more than ever when presenting these ads. In some cases interstitials prevent Googlebot from discovering and indexing the content that’s hidden under the ads. With some bad luck, this might lead straight into the deindexation of your whole website! You can perform a mobile-friendly test using the testing tool.Mitigate the Long-term EffectsWe do not have exact knowledge what the index will look like after the switch, but we can expect to see some large scale changes. Those effects might show up in the long-term, but are not guaranteed to occur. One is the page speed impact. Mobile users are more vulnerable to performance issues, because the average connection on mobile is slower than on desktop. Users are usually very impatient if it takes ages for a website to load. In fact, Google is taking steps to increase the effect that page speed has on rankings. It’s becoming a direct factor on mobile devices. Helpful tools in the Page Speed analysis are Google’s PageSpeed Insights and WebPageTest.Another supposed long-term change may be the PageRank flow in the scale of the entire web. It’s very unlikely that Google will chose to switch to a Mobile-only Index, and ignore desktop-only links altogether, but there might be a different approach to links present on both versus desktop-only links (and that’s a significant portion of external links today). This might lead to a change in the large-scale flow of PageRank, which might cause ranking fluctuations.Tied to the PageRank flow, there is another big factor that might change: the backlinks. Websites tend to link to external sources more freely on the desktop versions of their pages than on mobile, where every bit of space is worth its weight in gold. With Mobile-first Indexing Google might drop the value of desktop-only backlinks. Although this is just speculation, you might want to pay attention to the mobile backlinks as well and check whether your precious, high quality backlinks are present on mobile. TL;DRAt the end I’d like to present a simple checklist for you to take. If you’ve got it covered, you can calmly wait for the mobile index message in your Search Console.Check your website crawlability on mobile (with a smartphone User Agent).Make sure all your important links are present on mobile.Make sure all of your important content is present on mobile.Check whether meta tags, canonicals, hreflangs, and structured data are implemented correctly on mobile.Make sure your mobile site is actually mobile-friendly.Make your website (especially the mobile version) fast.Try to ensure indexation of important backlinks to your website after the Mobile-first update.Or get a responsive design if you can, that’s what Google and Users want in most cases.