About

About soft404scan

A free, open detector for soft 404s — pages that say "not found" but answer crawlers with HTTP 200.

A soft 404 is one of the quietest SEO bugs. The page tells a visitor the content is gone, but the server returns 200 OK (or 30x-redirects the URL to the homepage). Search engines can't tell it's missing, so they keep crawling and indexing it, burn crawl budget, and surface a "Soft 404" note in Search Console. The fix is simple — return a real 404 or 410 — but first you have to find them.

soft404scan never guesses from the status code alone. It pairs your URL with a synthetic, guaranteed-missing URL in the same directory and compares them — status code, redirect target, and content similarity — so it can tell a real page from a 200 that is really a "not found" page. The result is concrete pass/warning/issue facts plus the single signal that decided the verdict, with every rule published above. No black-box score.

It is deliberately narrow and honest. It reads server-rendered HTML only (like a crawler that doesn't run JavaScript) and, when it sees a single-page-app shell, it says so rather than guessing. Every rule is published in the methodology, results are concrete pass/warning/issue facts plus the one signal that decided the verdict, and there is no fake predictive score.

It runs on Cloudflare — a small serverless function fetches only public http(s) URLs, with private/loopback/metadata addresses blocked, redirects re-validated on every hop, and responses capped. No accounts, and we keep no logs of the URLs you check.

Built for developers, SEOs and site owners cleaning up crawl budget. Scan a URL →