Google API
Page Speed Test
Google APITest webpage loading performance, Core Web Vitals (LCP, FCP, CLS, TBT), Google Lighthouse audit scores, and actionable optimization opportunities via official Google PageSpeed API.
Google Lighthouse Audit Engine
Connecting to Google PageSpeed Insights API...
Running headless Chrome Lighthouse audit for Performance, Accessibility, Best Practices & SEO
Audited Webpage:
https://fastseotool.com
Mobile Profile
Google Lighthouse v11
98
Performance
Good (90-100)
100
Accessibility
Good (90-100)
96
Best Practices
Good (90-100)
100
SEO Score
Good (90-100)
Core Web Vitals & Page Metrics
Real-User Experience
Largest Contentful Paint (LCP)
GOOD
1.2 s
Measures when main content finishes loading (Target: < 2.5s)
First Contentful Paint (FCP)
GOOD
0.8 s
Marks first visible text/image rendering (Target: < 1.8s)
Cumulative Layout Shift (CLS)
GOOD
0.01
Measures visual stability & layout jumping (Target: < 0.1)
Total Blocking Time (TBT)
GOOD
40 ms
CPU responsiveness before user interaction (Target: < 200ms)
Speed Index
GOOD
1.1 s
How quickly page contents are visibly populated
Time to First Byte (TTFB)
GOOD
120 ms
Server response latency before HTML download
Rendered Snapshot
Above the Fold
Snapshot will render here after audit
Top Performance Opportunities & Diagnostics
Ranked by Potential SavingsQuick Steps
- 1 Enter any publicly accessible webpage URL into the search field.
- 2 Select your evaluation strategy: Mobile (simulating standard 4G networks) or Desktop.
- 3 Click Run Speed Audit to trigger official Google PageSpeed Insights Lighthouse analysis.
- 4 Review 4 Lighthouse category rings, Core Web Vitals (LCP, FCP, CLS, TBT), and prioritized optimization diagnostics.
Key Features
Official Google API: Direct integration with PageSpeed Insights API v5
4 Lighthouse Gauges: Performance, Accessibility, Best Practices, and SEO
Core Web Vitals: LCP, FCP, CLS, TBT, Speed Index & TTFB metrics
Rendered Screenshot: High-resolution visual capture of above-the-fold render
Why are Core Web Vitals critical for Google search rankings?
Google uses Core Web Vitals as official ranking signals in its search algorithm. Websites with fast loading (LCP under 2.5s), low layout shifts (CLS under 0.1), and responsive interactivity (TBT under 200ms) gain preferential placement on search results.
Why does Mobile score differ from Desktop score?
Google audits mobile devices with CPU throttling (emulating mid-tier mobile processors like Moto G4) and a simulated 4G connection. Desktop audits run on unthrottled high-speed connections, typically yielding higher overall scores.
How can I fix render-blocking resources?
Defer or asynchronously load non-critical JavaScript using async or defer script attributes, inline critical CSS above the fold, and preload key web fonts with link rel="preload".