--- type: "Article" title: "mobile-first indexing | technical SEO foundations" description: "How Google's mobile-first indexing works, its 2016 to 2024 timeline, and how to test that your mobile pages carry the same content as desktop." resource: "https://www.laurelinlabs.com/search-systems/mobile-first-indexing" tags: ["mobile-first-indexing", "technical-seo-foundations", "googlebot-smartphone"] generated: { by: "laurelin-site-build/2026-09-02", at: "2026-09-02T12:00:00+00:00" } status: "stable" stale_after: "2027-03-02T00:00:00+00:00" --- # Mobile-first indexing Mobile-first indexing means Google uses the mobile version of a site's content, crawled with the smartphone agent, for indexing and ranking. Google confirmed it, began experiments in 2016, declared the migration complete in October 2023 and stopped crawling the remaining sites with desktop Googlebot after 5 July 2024. It is infrastructure, not a ranking boost. For a site, anything missing from the mobile version (text, links, images, structured data, robots directives) is missing from Google's index. ## What is mobile-first indexing? Mobile-first indexing is Google's practice of crawling pages with its smartphone user agent and using the mobile version of the content for indexing and ranking. Before it, Google's systems typically evaluated the desktop version, which caused problems when the mobile page carried less content, as Google explained when it [began experiments on 4 November 2016](https://developers.google.com/search/blog/2016/11/mobile-first-indexing). There is one index, not a separate mobile index. Google said so explicitly when it [started migrating sites on 26 March 2018](https://developers.google.com/search/blog/2018/03/rolling-out-mobile-first-indexing). ## How does mobile-first indexing work? Googlebot Smartphone fetches and renders the page, and what it sees becomes the indexed document. Google's [best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing) say only the content shown on the mobile site is used for indexing, that robots meta tags should match across versions, and that Google won't load content that needs a swipe, click or typing to appear. For responsive sites the mobile and desktop HTML are the same, so parity is automatic. The risk sits with dynamic serving and separate mobile URLs, where different HTML goes to different devices. Google [recommends responsive design](https://developers.google.com/search/blog/2020/03/announcing-mobile-first-indexing-for) for new sites and advises against separate m-dot URLs. - Same primary text, headings and images on mobile as desktop. - Same internal links, including those in navigation. - Same structured data, titles, meta descriptions and robots directives. - No primary content that loads only on user interaction. ## What evidence is there that Google uses mobile-first indexing? The evidence label is Confirmed. Google documented each stage on its Search Central blog: experiments in 2016, migration from 2018, a plan in [March 2020](https://developers.google.com/search/blog/2020/03/announcing-mobile-first-indexing-for) to switch all sites, completion announced on [31 October 2023](https://developers.google.com/search/blog/2023/10/mobile-first-is-here), and the final switch of remaining sites to Googlebot Smartphone after [5 July 2024](https://developers.google.com/search/blog/2024/06/mobile-indexing-vlast-final-final.doc). Google has also been clear about what it is not. In 2018 it said mobile-first indexing is about how content is gathered, not how it is ranked, and carries no ranking advantage. ## What should a site do about mobile-first indexing? Audit the mobile rendered HTML as the version of record. Crawl with a smartphone user agent and JavaScript rendering, and compare against a desktop crawl: word count, headings, internal links, images, structured data and robots directives. Any difference is a difference in what Google indexes. The claim is falsifiable at page level: text that appears only on desktop should not be findable in Google results for that URL. Test a distinctive desktop-only sentence in a quoted search; if it never surfaces, mobile-first indexing is doing what Google says. ## Which Laurelin audit checks test for mobile-first indexing? The new check [Mobile version drops content, links or structured data present on desktop](https://www.laurelinlabs.com/audit/technical-foundations/359-mobile-version-drops-content-links-or-structured-data-present-on) compares the two rendered versions directly, which is the failure Google's best practices describe. Related existing checks: [Primary content only present after JavaScript](https://www.laurelinlabs.com/audit/technical-foundations/59-primary-content-only-present-after-js): content that depends on rendering, which Googlebot Smartphone must complete. [Lazy-loaded main content not triggered](https://www.laurelinlabs.com/audit/technical-foundations/63-lazy-loaded-main-content-not-triggered): lazy-loaded content Google will not trigger. [Meta robots noindex on a page that should be indexed](https://www.laurelinlabs.com/audit/technical-foundations/10-meta-robots-noindex-on-a-page-that-should-be-indexed): robots directives, which must match across versions. [robots.txt blocks CSS or JS needed to render](https://www.laurelinlabs.com/audit/technical-foundations/4-robots-txt-blocks-css-js-needed-to-render): blocked resources that stop the mobile page rendering. [Missing viewport meta](https://www.laurelinlabs.com/audit/topical-content/148-missing-viewport-meta): the basic mobile configuration. ## What are the common myths about mobile-first indexing? Sources: Google's [2018 rollout post](https://developers.google.com/search/blog/2018/03/rolling-out-mobile-first-indexing), its [best practices](https://developers.google.com/search/docs/crawling-indexing/mobile/mobile-sites-mobile-first-indexing) and its [June 2024 update](https://developers.google.com/search/blog/2024/06/mobile-indexing-vlast-final-final.doc). - Myth: there is a separate mobile index. Google says there is one index. - Myth: being switched to mobile-first indexing is a ranking boost. Google says it has no ranking advantage. - Myth: content in accordions or tabs on mobile is ignored. Google's best practices allow a different mobile design such as accordions or tabs, as long as the content is equivalent. - Myth: desktop Googlebot has disappeared entirely. Google says it may still appear for some features such as product listings and Google for Jobs. ## What are the key dates for mobile-first indexing? - 2016-11-04: Google begins mobile-first indexing experiments ([source](https://developers.google.com/search/blog/2016/11/mobile-first-indexing)) - 2018-03-26: Google starts migrating sites to mobile-first indexing ([source](https://developers.google.com/search/blog/2018/03/rolling-out-mobile-first-indexing)) - 2020-03-05: Google announces mobile-first indexing for the whole web ([source](https://developers.google.com/search/blog/2020/03/announcing-mobile-first-indexing-for)) - 2023-10-31: Google announces mobile-first indexing is complete ([source](https://developers.google.com/search/blog/2023/10/mobile-first-is-here)) - 2024-07-05: Remaining sites crawled only with Googlebot Smartphone after this date ([source](https://developers.google.com/search/blog/2024/06/mobile-indexing-vlast-final-final.doc)) ## FAQ ### Does mobile-first indexing affect rankings? Not directly. Google says it is about how content is gathered, not how it is ranked, but anything missing from the mobile version is missing from what Google indexes and ranks. ### Is mobile-first indexing finished? Google announced completion on 31 October 2023 and said the small set of remaining sites would be crawled only with Googlebot Smartphone after 5 July 2024. ### Do I need a separate mobile site? No. Google recommends responsive web design for new sites and suggests not using separate mobile URLs. Hub: [Technical Foundations](/topics/technical-foundations.md)