Google completed its rollout of mobile-first indexing in 2023. This means Google's crawler visits websites using a smartphone user agent (Googlebot Smartphone) by default, and the content it sees in that mobile view is what gets indexed and ranked — even for searches performed on desktop.
What this means in practice:
- If your mobile page has less content than your desktop page, that missing content will not be indexed
- Images or structured data only on the desktop version will not be seen
- A desktop-only or poorly responsive website will perform worse in rankings
Common issues: Hidden content that does not load on mobile, blocked resources (CSS or JavaScript disallowed in robots.txt), or interstitials that obstruct content on mobile.
What SearchVitals checks: The Performance audit includes a mobile friendliness check that tests whether pages render correctly on a mobile viewport and flags common mobile usability issues as findings.