Lazy Load Checker
Check if your website uses lazy loading for images. Get optimization recommendations.
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Best Practices
Use loading="lazy"
Add the native lazy loading attribute to images below the fold. This is supported by all modern browsers.
Avoid lazy loading above-the-fold
Images visible on initial page load should not be lazy loaded, as this delays LCP.
Add width and height
Always specify image dimensions to prevent layout shifts (CLS) when images load.
Use decoding="async"
For non-critical images, add decoding="async" to prevent blocking the main thread.
Consider IntersectionObserver
For more control over lazy loading, use IntersectionObserver for custom implementations.
Related Tools
About This Tool
Lazy loading is a critical web performance technique that defers the loading of images and other media until they are needed — typically when the user scrolls them into view. Implementing lazy loading correctly can significantly reduce initial page load time, lower bandwidth consumption, and improve Core Web Vitals scores, all of which contribute to better search engine rankings and user experience. Our free online lazy load checker analyzes any website URL to determine whether images are properly lazy-loaded and provides actionable optimization recommendations.
The tool inspects the HTML source of your web pages, looking for common lazy loading implementations including the native loading="lazy" attribute, Intersection Observer API usage, and popular JavaScript library approaches. It identifies images that are loading eagerly when they should be deferred, as well as lazy-loaded images above the fold that may hurt your Largest Contentful Paint (LCP) score. The checker provides a detailed report showing exactly which images need attention and how to fix them.
Beyond simple detection, the tool offers specific recommendations tailored to your website's technology stack. Whether you are using a CMS like WordPress, a static site generator, or a custom-built application, the lazy load checker provides implementation guidance that fits your workflow. All analysis happens through client-side fetching and parsing, with no data stored on external servers. This free tool requires no installation and works on any modern browser.
How to Use This Tool
Enter Your Website URL
Type or paste the full URL of the web page you want to check. The tool accepts any publicly accessible URL including HTTP and HTTPS pages.
Run the Analysis
Click the analyze button to fetch and inspect the page. The tool examines all image elements, their loading attributes, and their position relative to the viewport.
Review the Report
The results show a categorized list of images: properly lazy-loaded, eagerly loaded but candidates for lazy loading, and above-the-fold images that should load immediately. Each image is listed with its source and current loading behavior.
Implement Recommendations
Follow the specific code suggestions for each flagged image. The tool provides ready-to-use HTML snippets showing exactly how to add or adjust lazy loading attributes for optimal performance.
Re-Check After Changes
After implementing the recommendations, run the checker again on your updated page to verify that all images now have the correct loading strategy. Iterate until the report shows full optimization.
Advantages & Use Cases
Instant Performance Audit
Quickly identify which images on your page are missing lazy loading and which above-the-fold images are incorrectly deferred.
Actionable Recommendations
Get specific, ready-to-use code snippets for each flagged image so you can implement fixes immediately without guesswork.
Core Web Vitals Improvement
Proper lazy loading directly improves LCP and reduces initial page weight, contributing to better search engine rankings.
No Installation Required
Run the check directly in your browser on any device. No browser extensions, command-line tools, or software installations needed.
Completely Free and Private
The tool is free to use with no limits, and all analysis happens locally so your website data remains confidential.
Supported Formats & Recommendations
The lazy load checker analyzes standard HTML web pages and inspects img, picture, and source elements for lazy loading attributes. It detects the native loading="lazy" attribute, data-src patterns used by JavaScript lazy loading libraries (such as LazyLoad.js, Unveil.js, and Lozad), and Intersection Observer implementations. The tool also checks for CSS background-image lazy loading patterns where applicable. Results are categorized by loading strategy and position relative to the viewport, making it easy to prioritize optimization efforts.