Website PerformanceFree, no accountby Google (Chrome)

Lighthouse: Free Open-Source Website Audit in Chrome

Lighthouse is Google's free, open-source auditing tool built into Chrome DevTools. It scores any page on Performance, Accessibility, Best Practices, and SEO, with actionable audits under each. It is free with no account. As a lab tool it simulates conditions locally, so results vary and don't include real-user field data.

Provider:: Google (Chrome)
Access:: Free, no account
Account:: Not required
Best for:: Auditing a page's performance, accessibility, and SEO basics locally

Visit Lighthouse All free SEO tools

What is Lighthouse?

Lighthouse is the engine inside PageSpeed Insights, but running it yourself in Chrome DevTools gives you something PSI cannot: audits of localhost, staging, and logged-in pages, plus instant re-runs during development. Each audit produces four category scores with every check explained and linked to documentation.

For SEOs, the SEO category is a useful basics checklist (crawlable links, meta viewport, descriptive anchors), while Accessibility and Best Practices catches catch issues — missing alt text, low contrast, insecure requests — that affect both users and search quality signals.

Main features

Four-category scoring
Performance, Accessibility, Best Practices, and SEO scores out of 100, each expandable to individual audits.
Local and private-page audits
Audit staging sites, localhost, and authenticated pages that online testers cannot reach.
Device and throttling presets
Mobile simulation with network/CPU throttling, or desktop mode for higher-powered baselines.
Actionable documentation links
Every failed audit links to web.dev guidance explaining the fix.
CI and CLI integration
Run headless via Node, fail builds on score thresholds, and track regressions over time.

Is Lighthouse free?

Lighthouse is free and open source (Apache 2.0) with no account, no limits, and no paid tier. It ships inside every Chrome install under DevTools > Lighthouse.

No account. Runs in Chrome DevTools, as a Node CLI, or via the Chrome extension.

How to use Lighthouse

Open the page in Chrome (incognito, with extensions disabled for clean results) and press F12 to open DevTools.
Go to the Lighthouse tab, select Mobile or Desktop mode, check the categories you want, and click Analyze page load.
Read the category scores, then expand red and orange audits first — each names the exact elements or resources at fault.
Fix one category of issues, re-run, and compare. Keep a small log of scores so you can tell real improvement from run-to-run noise.
For pages you can't open publicly (staging, drafts), run Lighthouse there — then confirm with PageSpeed Insights after publishing.

Advantages and limitations

Where it shines

Free, unlimited, and works on private/staging pages.
Combines performance with accessibility and SEO-basics checks in one run.
Open source with CLI/CI support for regression tracking.
Every audit links to official fix documentation.

Where it falls short

Lab-only: no real-user field data, so pair with PSI or Search Console.
Scores fluctuate between runs; treat small deltas as noise.
The SEO category covers technical basics only — not content quality or authority.
Performance simulation on a fast developer machine may understate mobile problems.

Best use cases

Developers
Add Lighthouse CI thresholds to pull requests so performance regressions get caught before deploy.
Bloggers
Run the Accessibility audit on your theme and fix missing alt text and contrast issues it flags.
Theme shoppers
Audit theme demos before buying — a theme scoring under 70 on mobile performance will cost you later.

Alternatives to Lighthouse

PageSpeed Insights
Same engine plus real-user field data for public URLs. Official site
Rich Results Test
For validating structured data specifically, which Lighthouse only touches lightly. Official site
Screaming Frog SEO Spider
For site-wide crawling that page-level Lighthouse can't do. Official site

Lighthouse FAQ

Is Lighthouse the same as PageSpeed Insights?

Lighthouse is the audit engine; PageSpeed Insights runs Lighthouse in Google's lab and adds real-user field data. Use Lighthouse during development and PSI to see what visitors experience.

How do I open Lighthouse?

In Chrome, open DevTools (F12 or right-click > Inspect), then select the Lighthouse tab. Choose your categories and click Analyze page load.

Does a perfect SEO score mean my page will rank?

No. Lighthouse's SEO checks cover technical basics (indexability, meta tags, crawlable links). Rankings depend far more on content quality, relevance, and authority.

Sources and official documentation

Official sources are listed separately from RankMeDaily's commentary above. Product details verified 2026-10-13; confirm current pricing and limits on the provider's site.