Mobile by default, because that's how Google ranks pages. Add ?strategy=desktop to the URL to force desktop. The API endpoint accepts the same parameter.

Performance ≥ 90 is strong, 50–89 is OK, below 50 needs work. For Core Web Vitals: LCP < 2.5s, CLS < 0.1, INP < 200ms is the 'Good' threshold.

Why is the result different each time?

Lighthouse is sensitive to network and CPU variability, so repeat a check 3 times and use the median. The CrUX field data, when present, is more stable because it's aggregated from real Chrome users over the past 28 days.

Why doesn't this work for localhost?

PageSpeed Insights crawls from Google's servers, so it can only audit publicly reachable URLs. For local development, run Lighthouse directly via Chrome DevTools.

Free tool

Lighthouse + Core Web Vitals for any URL.

Run a Google PageSpeed Insights audit and pull the full Core Web Vitals breakdown (LCP, CLS, INP, FCP, TTFB) for any public URL. Mobile by default.

About

About this tool

Background

Page speed is one of the few performance signals Google has publicly confirmed as a ranking factor. The Core Web Vitals (Largest Contentful Paint, Cumulative Layout Shift, and Interaction to Next Paint) are the user-experience metrics Google tracks via the Chrome User Experience Report. A free page speed checker lets you spot-check any URL and see exactly where time is being spent.

This tool runs Google's official PageSpeed Insights API in the background, then surfaces the relevant scores in a clean view. The data is identical to what you'd get from running Lighthouse locally, minus the install.

How it works

Paste a full URL (including https://). The tool runs a Lighthouse audit via PageSpeed Insights and returns three category scores (Performance, Accessibility, SEO) plus the five Core Web Vitals values. CrUX field data is included when available.

Free anonymous use: 5 checks/day. Free account: 25/day. Each upstream PSI call counts against a global daily quota; if the global cap is reached you'll see a quota error and can retry tomorrow. Paid customers have a separate reserved pool that's not affected by free-tool traffic.

API

Need this for 1,000 domains?

The same data is available via the REST API. Pay only for what you use; credits never expire.

Get an API key

# Same data, programmatically. First 100 credits free on signup
curl "https://api.rankparse.com/v1/page-performance?url=https://example.com" \
  -H "X-API-Key: rp_your_key"

FAQ

Frequently asked questions

More checks on the free tools page.

Beyond the free tools

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