Mobile-First Indexing
Mobile-first indexing is Google's policy of indexing and ranking every site from its mobile version, crawled by Googlebot Smartphone. Content, links, structured data, and robots directives missing from the mobile page are missing from the index.
Under mobile-first indexing, the version of a page that enters Google's index is the one served to mobile devices. Googlebot Smartphone — the crawler announcing a mobile user-agent — is the primary crawler for every site, and what it fetches and renders is what search engine indexing evaluates. Google announced the shift in 2016 and declared the rollout fully complete in October 2023; every site is indexed mobile-first, with no opt-out.
The operative rule is parity: anything absent from the mobile version is absent from Google's view of the page. Text only the desktop layout shows is not indexed and cannot rank. Internal links only the desktop navigation carries pass no discovery or link signals — sections reachable only through them drift toward orphan pages. Structured data present only in desktop templates earns no rich results, and the mobile page's robots directives are the ones that count: a mobile-only noindex removes the page.
Responsive design satisfies parity by construction — one HTML document serves every device. Failures concentrate in setups that serve different HTML to mobile: separate m. domains built as stripped-down copies, and dynamic serving that trims content, links, or markup from the mobile response.
Quick facts
What does Googlebot Smartphone actually see?
Googlebot Smartphone fetches the page with a mobile user-agent and renders it at a mobile viewport, and that rendered result is the input to indexing. The desktop version is not what gets indexed.
Check the mobile view directly: the URL Inspection tool reports "Crawled as: Googlebot smartphone" and exposes the rendered HTML for the crawl. Content, links, or markup missing from that rendered HTML are missing from the index — regardless of what the desktop page contains.
What must match between the mobile and desktop versions?
Four elements require parity — each one missing on mobile is simply not indexed:
- Content — headings, text, images, and videos; content the mobile page omits cannot rank
- Internal links — mobile menus that drop desktop links cut page discovery and link equity
- Structured data — markup must be present on the mobile version to earn rich results
- Meta robots directives — Google obeys the mobile page's directives; a mobile-only noindex deindexes the page
Parity applies to the served HTML, not the visual layout: content collapsed into accordions, tabs, or hamburger menus on mobile is indexed at full weight. Content removed from the mobile DOM is not.
What are the common mobile-first indexing failures?
The failures are the setups where mobile HTML diverges from desktop HTML:
- Stripped-down m-dot sites — separate mobile domains carrying less content, fewer links, and less markup than their desktop counterparts
- Hidden mobile content — main content removed from the mobile DOM entirely, as opposed to collapsed behind accordions, which is fine
- Trimmed dynamic serving — mobile responses that drop the structured data or meta robots tags the desktop response includes
Audit by comparing the mobile rendered HTML against desktop for key templates, and verify what the live mobile page serves in its head with the Meta Tag Analyzer.
Frequently Asked Questions
Can a site opt out of mobile-first indexing?+
No. Google completed the rollout in October 2023 and applies mobile-first indexing to every site. The way to control what gets indexed is to control what the mobile version serves.
Is mobile-first indexing the same as mobile-friendliness?+
No. Mobile-first indexing determines which version of a page Google indexes; mobile-friendliness describes how usable that page is on a phone. A desktop-oriented page is still indexed mobile-first — from whatever its mobile rendering serves.
Do accordions and collapsed menus hurt indexing on mobile?+
No. Content present in the mobile HTML is indexed at full weight even when collapsed behind accordions, tabs, or menus. Only content removed from the mobile DOM is lost.