Core Web Vitals Checker — LCP, CLS & INP Overlay

Core Web Vitals Checker shows you how any page really performs — live, in a clean overlay you can drag anywhere. Built for developers and SEOs who want LCP, CLS, and INP at a glance without opening DevTools. Click the icon and a heads-up overlay appears with your Core Web Vitals, each rated Good, Needs work, or Poor using Google's thresholds. No sign-up, no ads, no tracking. ━━━━━━━━━━━━━━━━━━━━ WHAT YOU CAN DO ━━━━━━━━━━━━━━━━━━━━ ⚡ LIVE LCP, CLS & INP The three Core Web Vitals, updating as you scroll and interact with the page. 🟢 CLEAR RATINGS Color-coded Good / Needs work / Poor for every metric, using Google's official thresholds. 🔍 ACTIONABLE DIAGNOSTICS See the element responsible for LCP (click to highlight it on the page), the biggest layout shift and what caused it, plus TTFB and FCP for context. 🧲 DRAGGABLE OVERLAY Pin it anywhere on the page. Press Esc to close. Great for demos, audits, and screenshots. ━━━━━━━━━━━━━━━━━━━━ PRIVATE BY DESIGN ━━━━━━━━━━━━━━━━━━━━ - 100% free, forever - No account or sign-in - No ads, no analytics, no tracking - No network calls — everything runs on your device - Runs only on the tab you click, and only when you click it - Just two permissions (activeTab + scripting), and no remote code How it works: real Core Web Vitals accumulate during page load, so the overlay reads the browser's buffered performance data when you open it — capturing this page load without an always-on background script. INP grows as you interact. ━━━━━━━━━━━━━━━━━━━━ WHO IT'S FOR ━━━━━━━━━━━━━━━━━━━━ Front-end developers, performance engineers, and technical SEOs. Made by the team at seolust.com.