Image Optimizer Checker

The Image Optimizer Checker analyzes the images on a web page and reports whether they are well optimized for fast loading, examining factors like file size, dimensions, format, and whether modern compression is being used. It helps you identify the heavyweight images that slow down a page, hurt Core Web Vitals scores such as Largest Contentful Paint, and waste bandwidth on mobile connections. The output is an actionable list of images with their sizes and optimization opportunities.

The tool inspects the images referenced on the page, reads their byte size and pixel dimensions, and evaluates whether they use efficient formats like WebP or AVIF versus older, larger JPEG and PNG files. It commonly flags images that are served far larger than their displayed size, lack responsive sizing, or could be compressed further without visible quality loss. Because images often account for the majority of a page's total weight, these findings tend to deliver the biggest performance wins.

Typical use cases include pre-launch performance audits, diagnosing a slow page when the culprit is uncompressed hero images, and verifying that an image CDN or build pipeline is actually serving optimized assets. Developers also use it to confirm that next-gen formats and lazy loading are in place. It complements broader performance testing by isolating the image layer specifically.

A practical tip: serve images at the dimensions they are actually displayed, convert photographs to WebP or AVIF, and add width and height attributes to prevent layout shift. Use responsive srcset so mobile devices download appropriately sized assets, and enable lazy loading for below-the-fold images. For further reductions, run flagged assets through a dedicated image compression tool before re-uploading.