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Lazy Loading Checker

Check if lazy loading is configured for images on your page to speed up site performance

Check Results

This only checks lazy loading. For a comprehensive analysis, use the full page check.

You can also audit your entire site. Duplicate titles and descriptions, orphan pages, broken links between sections, and other site-wide issues can only be found with a full site audit.

If you don't have an SEO specialist, we can help fix the errors found.

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Why Lazy Loading for Images Matters

Lazy loading is a technique where images are loaded only when the user scrolls to them. Without lazy loading, the browser loads all images at once, even those far below the fold. This slows initial loading and worsens Core Web Vitals scores.

What This Tool Checks

  • loading="lazy" attribute — presence of native lazy loading on images
  • Above-the-fold images — first images should not be lazy (they're needed immediately)
  • Image count — how many images are on the page and how many have lazy loading
  • Iframes — lazy loading check for embedded videos and widgets
  • JavaScript libraries — detection of third-party lazy loading solutions

How Lazy Loading Works

  • Native approach — loading="lazy" attribute on <img> tags, supported by all modern browsers
  • Intersection Observer — JavaScript API for tracking element visibility in the viewport
  • Libraries — lazysizes, lozad.js, and other solutions for extended control
  • Above the fold — images visible on initial load should not be lazy, otherwise LCP will be delayed

Common Lazy Loading Mistakes

  • Lazy loading on above-the-fold images — delays LCP element rendering
  • Missing width and height on images — causes layout shifts (CLS) during loading
  • JavaScript-only lazy loading without fallback — if the script fails to load, images won't appear
  • No lazy loading for iframes — embedded videos and widgets should also load lazily

Frequently Asked Questions

Should lazy loading be applied to all images? ▶
No. Images visible on initial page load (above the fold) should not have loading="lazy". This will delay their display and worsen the LCP metric. Lazy loading is only needed for images below the first screen — those the user hasn't scrolled to yet.
Does lazy loading affect SEO? ▶
Lazy loading positively affects SEO as it speeds up page loading and improves Core Web Vitals. Google can index images with native lazy loading (loading="lazy"). But if lazy loading is implemented incorrectly via JavaScript, the search engine may not see the images.
Which lazy loading method is best? ▶
For most sites, the native loading="lazy" attribute is sufficient — it's supported by all modern browsers, requires no JavaScript, and is properly handled by search engines. JavaScript libraries are only needed for advanced control: custom animations, preloading, or support for very old browsers.

Other Checks

Indexing Check
robots.txt Check
sitemap.xml Check
SSL Certificate Check
HTTP/HTTPS Check
www Redirect Check
Title Tag Check
Meta Description Check
Headings Check
Canonical Check
Viewport Check
Open Graph Check
Encoding Check
Image Format Check
Alt Tags Check
Lazy Loading Check
Internal Links Check
External Links Check
Broken Links Check
Structured Data Check
Compression Check
HTML Size Check
Render-blocking JS Check
Mixed Content Check
HSTS Check
URL Structure Check