Core Web Vitals Checklist — Free Developer Tool

Progress

0 / 0 checked

Loading performance (LCP)

Largest Contentful Paint element identified and optimisedHero/above-the-fold images use modern formats (WebP/AVIF) and are sized correctlyCritical CSS is inlined or loaded without blocking renderFonts use font-display: swap or optional, with preloaded critical fontsServer response time (TTFB) is under 600ms

Interactivity (INP)

JavaScript bundles are code-split; nothing unnecessary loads on first paintLong tasks (>50ms) on the main thread are broken upThird-party scripts are deferred or loaded asyncEvent handlers avoid layout thrashing

Visual stability (CLS)

Images and embeds have explicit width/height or aspect-ratio setAds, embeds, and iframes reserve space before loadingWeb fonts don't cause visible layout shift on swapNo content is inserted above existing content without user interaction

Technical SEO basics

Every page has a unique title and meta descriptionCanonical URLs are set correctlySitemap.xml is generated and submitted to Search Consolerobots.txt doesn't accidentally block important pagesStructured data validates in Google's Rich Results Test