About this tool
Review image-loading exports before launch so critical images are not deferred, non-critical assets are not over-prioritized, and Core Web Vitals risk stays controlled.
The Image Lazy Loading Checker audits loading attribute usage to ensure above-fold and LCP-critical images load eagerly while below-fold content images properly defer with loading=lazy. It also evaluates fetchpriority hints to confirm that hero images receive high priority without competing with non-critical assets.
- Parses rows in URL|image|loading|fetchpriority|context|size format and normalizes page URLs with an optional base URL.
- Flags lazy-loaded critical images, eager below-fold images, high-priority misuse, and directive conflicts.
- Supports configurable below-fold eager payload budgets and per-page high-priority limits for practical remediation triage.
How to use Lazy Loading Checker
Supply image data including each image's loading attribute, fetchpriority value, viewport position, and criticality flag. The tool checks that LCP candidates are not lazy-loaded, below-fold images are deferred, and fetchpriority=high is reserved for the assets that actually need it.
When this tool is useful
- Audit loading and fetchpriority directives before launching templates, migrations, or performance-focused releases.
- Catch lazy-loaded hero/LCP images that can delay rendering and hurt Core Web Vitals.
- Prioritize non-critical images still marked eager or high-priority when they should defer.
Practical tips
- Keep above-fold and LCP images eager with clear high fetch priority, then lazy-load non-critical media by default.
- Set a byte budget for eager below-fold assets so accidental template regressions are easier to catch.
- Limit per-page high-priority images to only the truly critical visual assets to avoid resource contention.
Examples you can test
These examples show the kind of real input and reviewed output this tool is designed to support. Use them as a starting point before pasting your own production content, then compare the output with the destination system that will use the result. The goal is not only to produce a value, but to make the input assumptions, output format, and review step clear enough that the result can be trusted in a real workflow.
Find a lazy-loaded hero image
Example input
URL: / | Image: /hero.avif | loading: lazy | fetchpriority: high | Context: hero LCP | Size: 190 KB
Expected output
High-risk issue: the likely LCP image is lazy-loaded even though it should be requested early.
Hero and LCP images usually need eager loading, stable dimensions, and focused priority hints.
Catch eager below-fold payload waste
Example input
URL: /blog | Image: /gallery-08.webp | loading: eager | fetchpriority: auto | Context: below fold gallery | Size: 240 KB
Expected output
Warning: a below-fold image is loaded eagerly and may compete with initial page resources.
Below-fold content images are normally better candidates for native lazy loading.
Validation checklist
Run through these checks before copying the result into a CMS, codebase, spreadsheet, campaign, support ticket, or production document. Small formatting differences, unit assumptions, hidden whitespace, and platform-specific rules are common sources of mistakes in quick browser tools, so the final review should happen in the same context where the output will be used.
- Confirm above-the-fold and likely LCP images are not marked `loading="lazy"`.
- Review below-fold images for eager loading that increases initial transfer size without improving first viewport rendering.
- Check `fetchpriority="high"` together with loading behavior so the attributes do not send conflicting browser signals.
- Use byte budgets by page to prioritize large eager images before small icons or low-impact assets.
Why people use this tool
Lazy-loading an LCP image is one of the most damaging performance anti-patterns because it delays the browser from even requesting the most important visual element until JavaScript executes. Conversely, eagerly loading dozens of below-fold images wastes bandwidth and competes with critical resources, making correct loading attribute assignment essential for Core Web Vitals.
Related search intents
image lazy loading checker, loading lazy audit, above the fold image loading checker, native lazy load seo tool.