1. Source
A Lighthouse lab audit, or a stored audit of the same URL and device from the last six hours. The result identifies where its evidence came from.
Free tool, no account required
Free PageSpeed Checker: Lighthouse Lab Scores and Diagnostics
The Novaverb PageSpeed checker runs one Lighthouse lab audit of a public URL and reports performance, accessibility, best-practices and SEO scores, lab timing metrics and the top opportunities from that run.
Also known as: PSI, PageSpeed Insights, Lighthouse score
Evidence shown with sourceNo account requiredNo invented metrics
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Submit a public URL, domain, or keyword. Novaverb will show only the evidence this tool can actually retrieve or measure.
Definition
What is a PageSpeed checker?
A PageSpeed checker loads a page in a controlled lab and grades how it performs. The Novaverb PageSpeed Checker runs one Lighthouse lab audit on a simulated device and network, then reports the category scores, the lab timing metrics and the diagnostics from that run without re-weighting them.
Scope
What does the PageSpeed checker check?
The PageSpeed checker checks four Lighthouse categories, each scored from 0 to 100: performance, accessibility, best practices and SEO. For the same run the tool reports lab LCP, CLS, FCP and TTFB, and lists the top opportunities with the time each fix could save. INP is field data and appears only when available.
Who it is for
Who is the PageSpeed checker for?
The PageSpeed checker is for people who need a concrete list of what slows a page. A developer uses it to find render-blocking resources and oversized images before release, an SEO specialist uses it to brief technical work, and a site owner uses it to see where a template stands on mobile and desktop.
Why it matters
Why use a PageSpeed checker?
A PageSpeed checker turns a vague complaint about a slow page into named, reproducible diagnostics. A lab audit exposes loading, accessibility and implementation problems under fixed conditions, so the work can be prioritized by estimated time saved before the same weaknesses reach the experience of real visitors.
Method
How does the PageSpeed checker work?
The PageSpeed checker normalizes the address and runs the URL through a Lighthouse audit for the selected device, mobile or desktop. The category scores, lab timings and diagnostics from that run are reported with the published scoring methodology. Field INP is labeled separately, and the top opportunities are listed by estimated saving.
- We normalize the address and run the URL through Google's Lighthouse audit via PageSpeed Insights, or reuse a stored audit of the same URL and device from the last six hours.
- We report the category scores, lab timings and diagnostics from that run, with field INP labeled separately when available.
- We surface the top opportunities Lighthouse identifies, using its published scoring methodology.
Input
What do you enter into the PageSpeed checker?
Enter the public page address you want audited into the PageSpeed checker and choose mobile or desktop. Any address form is normalized, and the exact page you submit is audited. A page behind a login, a paywall or a geographic block cannot be audited, because the analyzer reaches it as an anonymous visitor.
Use it like this
yourdomain.comAny address form works - Lighthouse loads it in a controlled lab. http or https, with or without www, a bare domain or a full path - we normalize it for you.https://www.yourdomain.com/pageA specific public page is fine; we audit exactly what you submit.Avoid this
A page behind a login or paywallThe lab run cannot reach authenticated content, so the audit would not represent it.Result
What does a PageSpeed checker report contain?
A PageSpeed checker report contains four score gauges for performance, accessibility, best practices and SEO, a panel of lab timings for LCP, CLS, FCP and TTFB with field INP when available, and a list of top opportunities with estimated savings. The audited final URL and an evidence boundary note are shown with the result.
Reading it
How do you read a PageSpeed check result?
Read a PageSpeed check result as a to-do list, not a verdict. Lighthouse scores run from 0 to 100: 90 and above is good, 50 to 89 needs improvement and below 50 is poor. Start with the opportunity that has the largest estimated saving, and treat a small score change between runs as normal variation.
PageSpeed explained
Lighthouse scores are a diagnostic, not the ranking itself
A Lighthouse audit runs the page in a controlled lab and grades four categories from 0 to 100. It's the fastest way to find what's slowing a page down and get concrete opportunities - but Google ranks on real-user field data, so treat the lab score as a to-do list, not the verdict.
The four categories
- Performance - loading speed and responsiveness from lab metrics like LCP, TBT and CLS.
- Accessibility - automated checks for contrast, labels, and assistive-tech support.
- Best Practices - security, correct image sizing, and modern web standards.
- SEO - crawlable, mobile-friendly, correctly tagged pages.
Lab vs field
Lab data is reproducible and great for debugging. Field data (Core Web Vitals) reflects real users on real devices and networks. Use both: fix in the lab, confirm in the field.
Source
Where does the PageSpeed checker get its data?
The PageSpeed checker gets its data from a Lighthouse lab audit of the submitted URL, run through PageSpeed Insights in a simulated environment. The scores, timings and diagnostics all come from that audit. The one exception is INP, which is taken from the accompanying field dataset when it has enough real-user observations.
Limits
What does the PageSpeed checker not tell you?
The PageSpeed checker does not tell you how real visitors experience the page. Scores come from a single Lighthouse lab audit in a simulated environment, so they are a diagnostic and can differ from real-user field data. The accessibility score covers automatable checks only and is not proof of full accessibility.
Evidence
What does a PageSpeed check result prove?
A PageSpeed check result proves what one Lighthouse run scored on one simulated device and network, with its lab timings and top diagnostics. The result does not prove a stable number, because lab results vary between runs by design, and it does not predict rankings or the experience of every visitor.
2. Boundary
Scores come from a single Lighthouse lab audit in a simulated environment. Lab results are a diagnostic and can differ from real-user field data.
3. Next action
Use the finding to verify a problem, then connect a workspace when you need history, monitoring, or site-wide analysis.
Standards
Which standards does the PageSpeed checker apply?
The PageSpeed checker applies the Lighthouse documentation and the PageSpeed Insights methodology. Lighthouse defines the audits, the weightings and the scoring curve behind each category score. The PageSpeed Insights methodology defines how a lab run is produced and how it differs from field data. Both are reported as published, so a score can be reproduced independently.
GoogleLighthouse
Lighthouse audit engine
Runs the open-source Lighthouse audit and reports its category scores.
Read the specificationGooglePageSpeed
PageSpeed Insights methodology
Uses the PageSpeed scoring methodology and keeps lab timings separate from available field data.
Read the specificationWe list a standard only where this tool genuinely reads or measures against it. Where a signal is outside a live check, the result says so instead of implying coverage.
Verification
How can you verify a PageSpeed check result yourself?
Verify a PageSpeed check result by running Lighthouse on the same URL with the same device setting, for example from the browser developer tools. Expect the scores to land close, not identical, because each lab run varies. Compare the named opportunities as well as the scores before you trust either run.
Example
What does a typical PageSpeed checker finding look like?
A typical PageSpeed checker finding is a mobile audit where the performance score sits in the needs-improvement band while accessibility, best practices and SEO score well. Lab LCP is outside the good threshold, and the top opportunities name image sizing and render-blocking resources, each with an estimated time saving.
Cost
Is the PageSpeed checker free?
The PageSpeed checker is free and needs no account for a lab audit of one page on mobile or desktop. One run returns the scores, lab timings and opportunities. An account is needed when you want the audit saved as evidence, the score tracked over time, or a finding moved into a task that is rechecked.
In a workspace
What does a Novaverb workspace add to the PageSpeed checker?
A Novaverb workspace adds saved evidence, monitoring over time and site-wide analysis from a crawl to the PageSpeed checker, which audits one page per run. Site Health continues the job: it evaluates captured URLs against supported technical checks, orders findings by severity and records a fresh recheck after a fix.
When to go further
When is a free PageSpeed check not enough?
A free PageSpeed check is not enough when one lab run on one page cannot settle the question. Knowing how real users fare needs field data. Knowing whether a release regressed needs the same audit repeated over time. Knowing which templates are weak needs many pages measured, not the one submitted.
Next step
What should you do after running the PageSpeed checker?
After running the PageSpeed checker, work through the listed opportunities from the largest estimated saving down, commonly image compression and sizing, unused scripts, render-blocking resources and caching. Re-audit the page once the six-hour reuse window has passed to confirm the lab numbers moved, then check field data to confirm that real visitors see the improvement.
Related tools
Which free tools pair with the PageSpeed checker?
Free tools that pair with the PageSpeed checker complete the picture a lab run starts. The Core Web Vitals Checker reports real-user field data at the 75th percentile. The Server Response Time Checker splits a slow TTFB into DNS, TCP, TLS and request wait. The Image Compressor compresses JPG, PNG, WebP and AVIF images in your browser.
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Questions
What do people ask about the PageSpeed checker?
People ask the PageSpeed checker FAQ what a good Lighthouse performance score is, why lab results differ from real-user field data, and why a score changes between runs. They also ask which metrics are lab and which are field, how to fix the reported opportunities, and whether a high accessibility score means full accessibility.
What does the PageSpeed Checker report?
It runs one Lighthouse lab audit in a simulated environment and reports category scores, lab timing metrics and prioritized diagnostics. Field INP appears only when enough real-user data is available.
What is a good Lighthouse performance score?
Lighthouse scores run from 0 to 100. Broadly, 90 and above is good, 50 to 89 needs improvement, and below 50 is poor. Treat it as lab guidance, not a real-user guarantee.
Why do lab results differ from real-user field data?
Lighthouse runs one audit under simulated network and device conditions, so it may not match real visitors' varied hardware and connections. Lab data is reproducible and diagnostic; field data reflects actual user experience over time.
How do I fix the opportunities PageSpeed reports?
Work through the listed opportunities, commonly compressing and sizing images, deferring unused scripts, eliminating render-blocking resources, and enabling caching. Each opportunity estimates potential savings, so prioritize the ones with the largest estimated time reduction.
What is the difference between the PageSpeed and Core Web Vitals checkers?
PageSpeed runs a Lighthouse lab audit with simulated conditions and diagnostic opportunities. The Core Web Vitals Checker reports real-user field data at the 75th percentile. Use lab to diagnose, field to judge actual experience.
Which metrics are lab and which are field data?
LCP, CLS, FCP and TTFB on this panel come from the single simulated audit. INP is not produced by that lab run; it appears only when the accompanying field dataset has enough real-user observations.
Why does my score change between runs?
Each new Lighthouse run varies with network modeling, server response and page scripts. A stored audit of the same URL and device is reused for six hours, so a repeat check in that window shows the same scores. Compare audits taken further apart.
Does the accessibility score mean my site is fully accessible?
No. Lighthouse checks automatable accessibility issues only and cannot verify everything, like meaningful alt text or keyboard flows. A high score is a helpful baseline, not proof of full accessibility compliance.
Why run a PageSpeed audit?
A lab audit exposes reproducible loading, accessibility and implementation diagnostics. Use it to find technical work, then verify the outcome with field data; one lab run does not predict rankings or every visitor's experience.
Can one PageSpeed audit tell me how all my users experience the page?
No. It is one lab audit in a simulated environment representing a single test condition. To understand real visitors across devices and networks, pair it with real-user field data from the Core Web Vitals Checker.