Definition
Lighthouse is an open-source auditing tool built into Chrome DevTools. It produces 0-100 scores across Performance, Accessibility, Best Practices, and SEO categories, driven by a deterministic set of measurements and lab-simulated network conditions.
Why it matters
A Lighthouse run is the shortest credible way to show a prospect the delta between their current site and a rebuild. Sub-50 Performance is common on WordPress stacks we quote; 95+ is the bar we hit on every Next.js rebuild.
How we think about it
Lighthouse is necessary but not sufficient, a score of 98 is not the same as fast for a real user on a real network. We use Real User Monitoring via Vercel Analytics alongside Lighthouse for the truthful picture.