Lighthouse
ELI5 — The Vibe Check
Lighthouse is Google's report card for your website. It grades you on speed, accessibility, SEO, and best practices. Getting all 100s is the developer equivalent of a perfect SAT score — rare, bragged about, and slightly obsessive.
Real Talk
Lighthouse is an open-source automated tool by Google that audits web pages for performance, accessibility, progressive web apps, SEO, and best practices. It runs in Chrome DevTools, CI pipelines, or via PageSpeed Insights and provides actionable improvement suggestions.
When You'll Hear This
"Our Lighthouse performance score dropped to 40 after that carousel was added" / "Run Lighthouse in CI so we catch regressions before deploy"
Related Terms
First Paint
First Paint is the moment your browser stops showing a blank white screen and puts literally anything on it.
Performance Budget
A performance budget is like a calorie limit for your website.
Time to Interactive
Time to Interactive is when your page stops being a beautiful painting you can't touch and actually starts responding to clicks.