Free Core Web Vitals report for any website

VST Lite pulls Google's own Chrome UX Report data for any site: pass or fail, LCP, INP and CLS, about six months of weekly history, mobile vs desktop, and homepage vs whole site. Free, no signup.

e.g. https://www.example.com. Works with any site that has Chrome traffic data

What you'll see in your report

Historical Trends

25 weekly data points for LCP, INP and CLS. See exactly when performance got better or worse.

Pass/Fail Assessment

Instant visual status showing whether your site passes Google's Core Web Vitals thresholds at the 75th percentile.

Homepage vs. Origin

Compare your homepage performance against your site-wide average. See if specific pages are dragging you down.

Google's data stops at the site average

VST Lite shows what Google sees: a 28-day rolling score for the whole site or the busiest pages, and nothing at all for sites without enough Chrome traffic. Vital Signs Tracker measures every visit, so you can see which page is slow and why.

	VST Lite (free)	Vital Signs Tracker
Data	Google's Chrome UX Report	Every real visit to your site, from all browsers that report Web Vitals
Pages	Whole site plus the homepage, if Google has enough traffic	Every page, including cart, checkout and account pages Google never shows
Low-traffic sites	No data	Data from the first visit
Breakdowns	Mobile vs desktop	Traffic source (Google Ads vs organic), country, device, logged-in vs logged-out
What's causing it	Scores only	LCP, INP and CLS attribution: the element, the interaction and the timing breakdown
Freshness	28-day rolling, updated weekly	Daily, so you catch a bad deploy the same week
Reports	On demand	Scheduled email reports for you and your clients
Price	Free	From $29 a month

Start tracking with VST See plans and pricing

Use VST Lite in your AI assistant

VST Lite is also a free MCP server. Connect it to Claude, ChatGPT, Cursor or any MCP client and ask about any site's Core Web Vitals in plain English. No API key, no signup.

https://vitalsignstracker.com/mcp

Tools

get_core_web_vitals: current LCP, INP, CLS, FCP and TTFB, pass or fail, and the change over six months
get_core_web_vitals_history: weekly scores for about 25 weeks, to find when something got worse
compare_core_web_vitals: two to five sites side by side

Things to ask

Does example.com pass Core Web Vitals on mobile?
When did our LCP get worse this year?
Compare our site with our three biggest competitors.

Claude

Settings, Connectors, Add custom connector, then paste the URL above.

Claude Code

claude mcp add --transport http vst-lite https://vitalsignstracker.com/mcp

Cursor, Windsurf, VS Code and other clients

{
  "mcpServers": {
    "vst-lite": {
      "url": "https://vitalsignstracker.com/mcp"
    }
  }
}

Clients that only run local servers

npx mcp-remote https://vitalsignstracker.com/mcp

Core Web Vitals Report

www.example.com

Data through March 1, 2026 Passing CWV Top 5,000 site CrUX Popularity RankGoogle ranks origins by traffic volume into buckets: top 1K, 5K, 10K, 50K, 100K, 500K, 1M and 10M. This site falls in the top 5,000 most-visited origins in the Chrome UX Report dataset.

Which pages are dragging this score down?

Track every page with VST

📊

Homepage-specific data is available for this site. Your homepage has enough Chrome user traffic to generate its own scores, which can differ significantly from the site-wide average shown above. Individual pages often perform very differently to the site average.

🏠

You're viewing homepage-only scores. These scores reflect Chrome user data for your homepage URL specifically. They may differ from the site-wide average across all pages.

Core Web Vitals CWV

Largest Contentful Paint Largest Contentful Paint (LCP)Measures how long it takes for the largest visible element (image, heading, or text block) to finish rendering. This is the best proxy for perceived load speed: when users feel the page has "loaded".Good: ≤ 2.5s · Needs Improvement: 2.5–4.0s · Poor: > 4.0s Good

1.8s

75th percentile · Target: ≤ 2.5s

82% good 12% needs improvement 6% poor

Improved 320ms over 6 months

Interaction to Next Paint Interaction to Next Paint (INP)Measures the worst-case delay between a user interaction (click, tap, or keypress) and the next visual update. A low INP means the site feels snappy and responsive to every interaction.Good: ≤ 200ms · Needs Improvement: 200–500ms · Poor: > 500ms Good

128ms

75th percentile · Target: ≤ 200ms

89% good 8% needs improvement 3% poor

Improved 42ms over 6 months

Cumulative Layout Shift Cumulative Layout Shift (CLS)Measures unexpected visual movement of page content. A high CLS means elements are shifting around as the page loads, like a button moving just as you try to tap it. Common causes: images without dimensions, late-loading ads, and web fonts.Good: ≤ 0.1 · Needs Improvement: 0.1–0.25 · Poor: > 0.25 Needs Work

0.12

75th percentile · Target: ≤ 0.1

68% good 22% needs improvement 10% poor

Worsened by 0.03 over 6 months

Diagnostic Metrics

Time to First Byte Time to First Byte (TTFB)Measures the time from the user's request to the first byte of the server response. A slow TTFB indicates server-side issues: slow database queries, lack of caching, or distant hosting. It directly impacts every metric that follows.Good: ≤ 800ms · Needs Improvement: 800–1800ms · Poor: > 1800ms Good

420ms

75th percentile · Target: ≤ 800ms

78% good 16% needs improvement 6% poor

Improved 130ms over 6 months

First Contentful Paint First Contentful Paint (FCP)Measures when the first text or image becomes visible. FCP is the user's first visual feedback that the page is loading. A fast FCP reassures users that something is happening, even before the full page renders.Good: ≤ 1.8s · Needs Improvement: 1.8–3.0s · Poor: > 3.0s Good

1.2s

75th percentile · Target: ≤ 1.8s

84% good 11% needs improvement 5% poor

Improved 400ms over 6 months

Core Web Vitals Trends

The three metrics Google uses to assess your site's user experience. 75th percentile values over ~10 months, updated weekly.

Largest Contentful Paint (LCP)

Good ≤ 2.5s Needs Improvement Poor > 4.0s

Interaction to Next Paint (INP)

Good ≤ 200ms Needs Improvement Poor > 500ms

Cumulative Layout Shift (CLS)

Good ≤ 0.1 Needs Improvement Poor > 0.25

Diagnostic Metrics

These aren't part of Google's Core Web Vitals assessment, but they're critical for diagnosing performance issues and understanding what's driving your CWV scores.

Time to First Byte (TTFB)

Good ≤ 800ms Needs Improvement Poor > 1800ms

First Contentful Paint (FCP)

Good ≤ 1.8s Needs Improvement Poor > 3.0s

Free Core Web Vitals report for any website

Historical Trends

Pass/Fail Assessment

Homepage vs. Origin

Google's data stops at the site average

Use VST Lite in your AI assistant

Tools

Things to ask

Claude

Claude Code

Cursor, Windsurf, VS Code and other clients

Clients that only run local servers

No Data Available

Core Web Vitals Report

Passing Core Web Vitals Assessment

12-Week Speed History

Core Web Vitals Trends

Diagnostic Metrics

Free Core Web Vitals report for any website

Historical Trends

Pass/Fail Assessment

Homepage vs. Origin

Google's data stops at the site average

Use VST Lite in your AI assistant

Tools

Things to ask

Claude

Claude Code

Cursor, Windsurf, VS Code and other clients

Clients that only run local servers

No Data Available

Passing Core Web Vitals Assessment

12-Week Speed History

Core Web Vitals Trends

Diagnostic Metrics

This is a 28-day average. Your visitors had a day-by-day experience.