Broken Image Checker: Find Every Failing Asset Before Your Users Do

A missing image doesn't crash your page. That's what makes it insidious. The layout shifts slightly, an alt attribute gets rendered as fallback text if you're lucky, and the user gets a blank rectangle where your carefully chosen product photo was supposed to be. The page technically "works." It just looks broken.

Broken images accumulate quietly. CDN migrations leave old URLs pointing nowhere. CMS uploads get reorganized without redirects. File names get corrected for case sensitivity on a new Linux server after being fine on a case-insensitive Mac. The image was there when you deployed. It isn't now.

What counts as a broken image

The obvious case is a src attribute pointing to a 404. But the full scope is broader:

• -HTTP 404 - the image simply doesn't exist at that URL anymore.
• -HTTP 403 - the image exists but the server is blocking access. Common with hotlink-protected CDNs.
• -SSL errors - an image served over HTTP on an HTTPS page is blocked by browsers as mixed content.
• -Slow-loading images - technically loading, but taking 8+ seconds to respond. From a user's perspective, indistinguishable from broken.
• -Missing alt text - not a broken image per se, but a broken experience for screen reader users and a missed SEO signal for everyone.

Beyond images: scripts and stylesheets

A broken image degrades the visual experience. A broken JavaScript file can break functionality entirely. A missing stylesheet can make your site look like it's being rendered in 1997. These fail silently too - the browser console logs an error, but unless you have your dev tools open on that specific page, you'll never know.

The CDN migration trap

This is where most broken assets come from in production. You move your static files from one bucket or CDN to another. You update the references in your build config. But there are always references you missed - hardcoded in old blog posts, in CMS content fields, in email templates that are still live, in CSS files that reference image paths relatively.

The SEO angle

Search engines index images. They read alt text to understand what an image depicts, and they factor image availability into their assessment of page quality. A product page with three broken product images is not a high-quality product page, regardless of how good the surrounding text is.

Google's image search also sends meaningful traffic to sites that maintain good image hygiene. Missing images means missing traffic from that channel, and missing alt text means your images are invisible to that crawl regardless of whether the files exist.

Finding them across your whole site

The challenge with broken images is that they don't show up on the pages you regularly visit. The homepage looks fine. The main product pages look fine. It's the blog post from two years ago, the archived event page, the documentation section nobody's updated - these are where broken images hide.

A crawler checks every page it finds, follows every src attribute on every image tag, and requests the asset. If it gets anything other than a 2xx, it reports it. That's the only way to get comprehensive coverage.