Image SEO Tool

Alt text, SEO filenames, WebP conversion, and responsive srcset markup

Why image SEO details matter

Alt text: accessibility first, SEO second

Alt text exists for users who cannot see images. Screen readers read it aloud; search engines use it to understand image content. Google's guidance: write for people, not algorithms.

"Google uses alt text along with computer vision algorithms and the contents of the page to understand the subject matter of the image."

Keep alt text concise and descriptive. Describe what's in the image as you would to someone who can't see it. Skip "image of" or "photo of." Google already knows it's an image.

File names are a ranking signal

The filename is one of the signals Google uses to understand an image before it even downloads it. DSC_4821.jpg tells Google nothing. red-oak-dining-table-walnut-legs.jpg does.

"The filename can give Google very light clues about the subject matter of the image. For example, my-new-black-kitten.jpg is better than IMG00023.JPG."

WebP reduces page weight without visible quality loss

WebP consistently beats JPEG and PNG on file size without a visible quality drop. Smaller files load faster, which directly affects Largest Contentful Paint (LCP), a Core Web Vital Google uses in ranking.

"WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller than comparable JPEG images."

WebP is supported in all modern browsers. There is no meaningful reason to serve JPEG or PNG to modern browsers when WebP is available.

Responsive images prevent wasted bandwidth

Serving a 2400px image to a 375px phone screen wastes bandwidth and hurts load times. The HTML srcset attribute lets browsers request only the size they need.

"There is no need to embed such large images on the page if it is being viewed on a mobile screen. Doing so can waste bandwidth; in particular, mobile users don't want to waste bandwidth by downloading a large image intended for desktop users, when a small image would do for their device."

The sizes attribute tells the browser how wide the image will render at each breakpoint, so it can pick the right source before CSS even loads. Done correctly, it's one of the highest-impact performance fixes you can make in plain HTML.