Mobile-first indexing: what it means for your site

Google uses the mobile version of a page's content, crawled with its smartphone crawler, for indexing and ranking. This is called mobile-first indexing, and it now applies to essentially all sites.

What it means in practice

If something is on your desktop pages but missing from the mobile version, Google may not see it. For a responsive site, where the same HTML is served to all devices, there is usually nothing to do. Problems appear when the mobile version is different.

Differences that cause problems

• Less content on mobile. Text, sections or reviews removed from the mobile layout to save space. Hiding content in tabs or accordions is fine; removing it is not.
• Missing structured data or different metadata (titles, descriptions, robots tags) on the mobile version.
• Images or videos that load on desktop but not on mobile, or that are lazy-loaded only after interaction.
• Blocked resources on mobile URLs, such as CSS or JavaScript disallowed in robots.txt.
• Separate mobile URLs (an m. site) that are incomplete, wrongly linked to their desktop equivalents, or redirect every page to the mobile home page.

What to check

1. Use the URL Inspection tool in Google Search Console: it shows how Googlebot smartphone sees the page, including the rendered HTML and screenshot.
2. Compare the mobile and desktop versions of your key templates: main content, headings, internal links, structured data and images should match.
3. Crawl the site as a smartphone with a crawler such as Screaming Frog, which can use a mobile user agent.
4. Check speed on mobile in PageSpeed Insights, which reports mobile and desktop separately.

The simplest approach

A responsive design, where the same URL serves the same HTML to every device and CSS adapts the layout, avoids almost all mobile-first indexing problems. Google recommends it as the easiest pattern to implement and maintain.

For more technical checks, see A technical SEO checklist for new sites.