AEO Engine free tool

Free Core Web Vitals Test — Check LCP, INP, and CLS

A Core Web Vitals test checks your page against Google's three page-experience metrics: LCP (Largest Contentful Paint) for loading speed, INP (Interaction to Next Paint) for interactivity, and CLS (Cumulative Layout Shift) for visual stability. AEO Engine adds an AI search layer: whether your page loads fast enough for AI crawler budgets like GPTBot, ClaudeBot, and PerplexityBot, and whether slow rendering or JavaScript bloat is blocking AI answer engines from citing your content.

Who this tool is for: Built for SEO leads, site engineers, founders, and agencies who need a fast Core Web Vitals check with actionable remediation. Use it before content launches, during page speed audits, or before running a full AEO report to ensure pages are fast for both Google rankings and AI search crawlers.

What this tool measures

  • LCP (Largest Contentful Paint) — loading speed estimate with Good ≤ 2.5s threshold
  • INP (Interaction to Next Paint) — interactivity estimate with Good ≤ 200ms threshold
  • CLS (Cumulative Layout Shift) — visual stability estimate with Good ≤ 0.1 threshold
  • AI crawler readiness — speed budget for GPTBot, ClaudeBot, PerplexityBot, and GoogleExtended
  • Optimization signals: compression, CDN, caching, image weight, JS payload
  • 10-point speed health checklist with AI-crawl relevance

How it works

  1. Enter your page URL
  2. The tool fetches and analyzes page resources, headers, and payload
  3. Review LCP, INP, and CLS estimates with Good/Needs Improvement/Poor status
  4. Check the AI crawler accessibility score and optimization signals
  5. Run the full AEO report or book a strategy call to implement fixes

Why it matters for AI search and revenue

Core Web Vitals are a confirmed Google ranking signal, but in 2026 they also affect whether AI answer engines can efficiently crawl, parse, and cite your content. Slow pages and JavaScript bloat create barriers for both users and AI systems. If your page takes too long to load, AI crawlers may skip it entirely — meaning your content never makes it into AI-generated answers.

How AEO Engine executes beyond the tool

AEO Engine turns the CWV diagnosis into implementation: optimize LCP by reducing server response times and render-blocking resources, improve INP by breaking up long JavaScript tasks, reduce CLS by setting explicit dimensions on images and ads, and add AI crawler directives so answer engines can efficiently parse and cite your content. The free tool diagnoses; managed AEO execution ships the fixes.

Use cases and examples

  • Check LCP, INP, and CLS before launching a new marketing page
  • Identify whether JavaScript bloat is slowing AI crawler access
  • Audit page speed across competitor pages before rewriting content
  • Verify that image weight and compression are not blocking Core Web Vitals thresholds
  • Bridge a quick speed check into a full AEO report with AI visibility scoring

Comparison and alternatives

Google PageSpeed Insights provides the most accurate field data from CrUX. GTmetrix, DebugBear, and WebPageTest offer deeper waterfall analysis. This free tool is narrower by design: it provides a fast lab-style estimate plus an AI crawler readiness score that traditional tools do not offer. Use PageSpeed Insights for field data; use AEO Engine to bridge speed fixes into AI search visibility.

FAQ

What is a Core Web Vitals checker?

A Core Web Vitals checker tests a URL against Google's three Core Web Vitals metrics: LCP (loading), INP (interactivity), and CLS (visual stability). A good checker shows pass/fail status, explains what is causing poor scores, and recommends fixes.

What is a good LCP score?

A good Largest Contentful Paint (LCP) value is 2.5 seconds or less at the 75th percentile of page loads, segmented across mobile and desktop devices.

What is a good INP score?

A good Interaction to Next Paint (INP) value is 200 milliseconds or less. INP measures a page's overall responsiveness to user interactions. It replaced First Input Delay (FID) in March 2024.

What is a good CLS score?

A good Cumulative Layout Shift (CLS) value is 0.1 or less. CLS measures unexpected visual stability shifts during page load and interaction.

Does passing Core Web Vitals guarantee rankings?

No. Google confirms Core Web Vitals are used by ranking systems, but page experience is one of many signals. Good Core Web Vitals scores do not guarantee top Google rankings.

Why do lab and field data differ?

Lab data comes from controlled tests in a simulated environment. Field data comes from real Chrome users (CrUX). Lab data is useful for debugging; field data reflects actual user experience. They often differ because real users have varying devices, networks, and locations.

Next step

Test your Core Web Vitals score. Check LCP, INP, and CLS with AEO-specific remediation guidance for Google and AI search visibility. Free Core Web Vitals checker from AEO Engine.

Test Core Web Vitals