Turn Lighthouse audits into a fix plan.

CLAUDE.md is a plain markdown file Claude Code reads at the root of your repository to understand the project context. This tool generates one scoped to your failing Lighthouse audits — including the throttling profile used, third-party impact, main-thread breakdown, and the list of currently passing audits so the agent doesn't regress them.

It opens Claude Code via the claude://code/new deep link with the generated fix plan pre-filled as the initial prompt. You need the Claude Code desktop app installed for the deep link to resolve.

All four Lighthouse categories: Performance, Accessibility, Best Practices, and SEO. Any audit scoring below 0.9 is included with an actionable fix suggestion and a ranked offender list.

Start with the worst-scoring audits. Common wins: defer non-critical JavaScript, preload the LCP image, set explicit width and height on images to prevent layout shift, enable text compression at the server or CDN, eliminate render-blocking CSS, and remove unused third-party scripts. This tool ranks offenders by potential savings (in ms or KB) so you fix the highest-impact issues first.

Core Web Vitals are three user-experience metrics Google uses as ranking signals: Largest Contentful Paint (LCP) under 2.5 s, Interaction to Next Paint (INP) under 200 ms, and Cumulative Layout Shift (CLS) under 0.1. Lighthouse and PageSpeed Insights report these alongside the audits that affect them.

Yes. Install PageSpeed → CLAUDE.md from the Chrome Web Store. It analyzes the active tab with one click — no URL copy-pasting, and it works on private staging URLs you're already authenticated to.

Yes, given proper context. The CLAUDE.md this tool generates is designed specifically as agent context — it includes the throttling profile, prescriptive fix per audit, ranked offenders, and a "do not regress" list of currently passing audits. Most audits in Performance, Accessibility, Best Practices, and SEO can be resolved by Claude Code with this brief as input.

Lighthouse uses three thresholds per category: 90–100 Good (green), 50–89 Needs Improvement (orange), 0–49 Poor (red). For SEO ranking and Core Web Vitals, aim for 90+ on Performance with all three Core Web Vitals in the Good range.

LCP measures how quickly the largest visible element (usually the hero image or main heading) renders. Aim for under 2.5 seconds. Common fixes: preload the LCP image, avoid lazy-loading it, reduce server response time, eliminate render-blocking CSS.

TBT measures how long the main thread is blocked by long JavaScript tasks during page load. Aim for under 200 ms. Fixes: code-split heavy bundles, defer non-critical scripts, replace synchronous third-party scripts, move heavy work to Web Workers.

CLS measures unexpected layout movement during page load. Aim for under 0.1. Fixes: set explicit width and height on images and embeds, reserve space for dynamically inserted content like ads, avoid inserting content above existing content unless triggered by user action.

The web app requires the URL to be reachable by Google's PageSpeed Insights API, which means publicly accessible HTTPS. For localhost or private staging, install the Chrome Extension and use it on a deployed staging URL. Future versions of the extension may run Lighthouse locally to support localhost.

Typically 10–30 seconds, depending on the page complexity and Google's queue. The audit runs in Google's cloud, not in your browser, so it doesn't consume your bandwidth or CPU.

The URL you submit is sent to Google PageSpeed Insights to run the audit. It is not stored on our servers. See the privacy policy for full details. No account is required and we do not collect personal data.

They come straight from Lighthouse's own audit results. We surface the first few items per audit so the brief stays actionable rather than exhaustive — Claude Code can use the patterns to find similar issues across the codebase.