How this SEO checker runs Lighthouse
The checker runs Google's Lighthouse on your URL in a real Chromium browser, and falls back to Google PageSpeed Insights if that run fails. It returns the four Lighthouse scores, Performance, Accessibility, Best Practices and SEO, plus Largest Contentful Paint, Cumulative Layout Shift, First Contentful Paint and Total Blocking Time.
Pick mobile, the default and what Google indexes first, or desktop. Results are cached for 24 hours per URL and mode, so running the same check again within a day returns the same report.
Reading the scores
Each score runs from 0 to 100: 90 and above is good, 50 to 89 needs work, below 50 is poor. The SEO score checks the basics a crawler needs, such as a title, a meta description, crawlable links, a valid hreflang and a page that is allowed to be indexed.
The timings are lab data from one simulated load. Google ranks on field data collected from real Chrome users, so treat the lab numbers as a way to find and compare problems, not as the figures Google sees.
Frequently asked questions
Why does my Lighthouse score change from one run to the next?
Network timing, server load and third-party scripts vary between loads, so performance scores move by a few points even when nothing changed. Compare trends rather than single runs.
Is a 100 SEO score enough to rank?
No. The Lighthouse SEO score checks technical prerequisites that let a page be crawled and understood. Ranking depends on content, links and relevance, which Lighthouse does not measure.
What are good Core Web Vitals values?
Google's thresholds are a Largest Contentful Paint under 2.5 seconds and a Cumulative Layout Shift under 0.1. Interaction to Next Paint, the third vital, can only be measured on real users; Total Blocking Time is its closest lab equivalent.