HTTP Status & Header Checker

Look up any HTTP status code and audit response headers for SEO, security and caching best practice.

Status Code

Header Audit

Status Codes and SEO

The HTTP status code is the single most important technical signal a crawler receives about a URL. 200 means "index me". 301 means "I moved, credit the new URL". 404 means "gone". 500 means "retry later — I'm broken".

Common SEO-Relevant Codes

  • 200 OK — normal, indexable.
  • 301 Moved Permanently — permanent move, passes full equity.
  • 302 Found — temporary. Rarely the right choice in production.
  • 404 Not Found — page doesn't exist. Soft 404s (200 with "not found" content) confuse crawlers.
  • 410 Gone — page existed but is now permanently removed. Google deindexes faster than 404.
  • 429 Too Many Requests — rate limiting. Crawler backs off and retries.
  • 500 Internal Server Error — retry later. Persistent 500s drop URLs from the index.
  • 503 Service Unavailable — use for planned maintenance, but include Retry-After.

Headers That Matter

HeaderPurpose
Content-TypeMust be text/html; charset=utf-8 for HTML pages.
Strict-Transport-SecurityHSTS — forces HTTPS for future requests.
X-Content-Type-OptionsShould be nosniff.
X-Frame-OptionsDENY or SAMEORIGIN to prevent clickjacking.
Referrer-PolicyControls referrer leakage.
Cache-ControlControls CDN and browser caching. Impacts Core Web Vitals on repeat visits.
Content-EncodingShould include gzip or br for text assets.
X-Robots-TagEquivalent of meta robots but at HTTP level — applies to PDFs, images too.

Why Headers Matter for SEO

HSTS reduces the risk of protocol downgrade attacks. Missing Cache-Control forces repeat visitors to re-download assets, directly hurting INP on return visits. Missing Content-Encoding can double your transfer size. A wrongly-set X-Robots-Tag can accidentally noindex an entire section of your site.

Soft 404s — The Silent Killer

A soft 404 is a page that returns 200 OK but shows "not found" content. Google has to guess whether the page is empty, dead, or simply a thin page. Persistent soft 404s waste crawl budget and can pull authority from the whole site. If content is gone, return a genuine 404 or 410 — never a 200 with a "nothing here" message.

HTTP Header FAQ

Is 301 always better than 302 for SEO?

Yes for permanent moves. 301 passes ~all link equity; 302 passes very little. If you're not sure whether a move is temporary, use 301 — you can always change it later, and search engines recrawl.

What is a 410 and when should I use it?

410 Gone means the resource existed but is permanently gone. Google deindexes 410 faster than 404 because 410 is a stronger "don't bother coming back" signal.

Does Content-Encoding affect SEO?

Indirectly. gzip or brotli compression reduces transfer size, improving LCP and overall page speed. Both are Core Web Vitals signals.

What does X-Robots-Tag do?

It applies noindex, nofollow or other robots directives at the HTTP level — useful for non-HTML resources (PDFs, images) where you can't add a meta tag.