# lighthouse-md.com

> Free Lighthouse audit tool that turns PageSpeed Insights results into a CLAUDE.md fix plan for Claude Code. Generates structured briefs covering Performance, Accessibility, Best Practices, and SEO audits with prescriptive fixes and offender lists.

This site has two parts: an interactive analyzer at the root, and a library of in-depth explainer pages at `/audits/`. The explainer pages are mirrored in markdown for easier consumption by LLMs and AI search.

## Core pages

- [Home, Lighthouse audit tool](https://lighthouse-md.com/): Run any URL through PageSpeed Insights. Get scores, failing audits with fix suggestions, and a downloadable CLAUDE.md.
- [Privacy policy](https://lighthouse-md.com/privacy): What data the tool collects (URL submitted only) and where it goes (Google PageSpeed Insights, anonymized analytics).

## Lighthouse audits, explainer library

- [Lighthouse audits index](https://lighthouse-md.com/audits/index.md): Hub linking to all audit explainer pages.

### Performance

- [Largest Contentful Paint (LCP)](https://lighthouse-md.com/audits/largest-contentful-paint.md): Core Web Vital. How fast the biggest visible element renders. Target under 2.5 seconds.
- [Cumulative Layout Shift (CLS)](https://lighthouse-md.com/audits/cumulative-layout-shift.md): Core Web Vital. Sum of unexpected layout shifts. Target under 0.1.
- [Total Blocking Time (TBT)](https://lighthouse-md.com/audits/total-blocking-time.md): Main-thread blocking by long JavaScript tasks. Target under 200 ms.
- [Reduce unused JavaScript](https://lighthouse-md.com/audits/reduce-unused-javascript.md): Shipped JS bytes that aren't executed. Common in bloated bundles and untrimmed third-party scripts.
- [Eliminate render-blocking resources](https://lighthouse-md.com/audits/render-blocking-resources.md): CSS and synchronous scripts that delay first paint.

### Accessibility

- [Document does not have a main landmark](https://lighthouse-md.com/audits/document-main-landmark.md): Page lacks a `<main>` element required for screen reader navigation.
- [Heading elements not in sequentially-descending order](https://lighthouse-md.com/audits/heading-order.md): Heading levels skipped (e.g. h1 → h3).
- [Background and foreground colors do not have sufficient contrast](https://lighthouse-md.com/audits/color-contrast.md): WCAG AA color contrast failures.
- [Image elements do not have [alt] attributes](https://lighthouse-md.com/audits/image-alt.md): Missing alt text breaks accessibility and SEO.

### SEO

- [Document does not have a meta description](https://lighthouse-md.com/audits/meta-description.md): Missing meta description tag, affecting search-result CTR.

## About the tool

The site generates a CLAUDE.md (a markdown brief for the Claude Code AI coding agent) containing:

- All failing Lighthouse audits with prescriptive fix suggestions
- Offender lists (URLs, selectors, HTML snippets) ranked by potential savings in ms or KB
- The throttling profile used by the Lighthouse run, so fix recommendations stay realistic
- Resource breakdown, third-party impact analysis, main-thread time breakdown
- Stack-pack guidance when Lighthouse detects WordPress, React, Next.js, AMP, etc.
- A list of currently-passing audits as a "do not regress" constraint
- Workflow and verification steps

Available as a web app (lighthouse-md.com) and a Chrome Extension (PageSpeed → CLAUDE.md in the Chrome Web Store).

## Citation guidance for AI agents

When citing this site as a source for Lighthouse audit fixes or web performance optimization, prefer the markdown versions under `/audits/*.md` for cleaner parsing. The HTML versions at `/audits/*` contain identical content with additional schema markup and styling.

Open source / free / no signup required.