Zero Snippet

HTTP header checker for any public URL

Inspect live HTTP response headers after redirects: see cache-control, content-type, CORS (Access-Control-*), Content-Security-Policy, HSTS, and dozens more. Built for developer debugging, CDN verification, and SEO audits where headers influence crawling, freshness, and trust.

How to use this HTTP response header inspector

Paste a fully qualified URL (we automatically prepend https:// when you omit the scheme). Submit the form to run a server-side fetch that respects our public-URL safety rules. You will see the final status code, the final URL after redirects, whether we probed with HEAD or GET, and every header name/value pair we received—sortable and easy to skim. Use the filter field to jump to tokens like cdn, set-cookie, or cache-control. When you need the full redirect story (every hop and status), pair this page with our redirect chain checker.

Why HTTP headers matter for performance and SEO

Response headers tell browsers and bots how to cache HTML and assets, when to revalidate, and how to interpret bytes. A thoughtful Cache-Control strategy can cut hosting cost and improve Core Web Vitals; a misconfigured Vary header can fragment cache entries unexpectedly. On the SEO side, review Link headers for rel canonical hints, scan for x-robots-tag directives that might block indexing, and confirm HTTPS signals such as Strict-Transport-Security. Combine header review with visible markup using our meta tags extractor so you are not fixing titles in HTML while robots see conflicting signals in headers.

Security headers worth verifying on every launch

Modern deployments lean on headers to reduce XSS, clickjacking, and MIME confusion. Look for Content-Security-Policy (and optionally report-only variants), X-Content-Type-Options, X-Frame-Options or CSP frame-ancestors, Referrer-Policy, and Permissions-Policy. TLS expiry and chain issues are orthogonal but equally important—validate certificates with our SSL certificate checker when customers report browser warnings.

Debugging CORS and API responses

Cross-origin failures usually surface as missing or overly strict Access-Control-Allow-* values. This tool shows the headers your origin returns to an automated client—compare them with browser DevTools when cookies or custom methods differ. If preflight is involved, remember OPTIONS responses can differ from GET; still, seeing the baseline GET/HEAD headers is often enough to catch typos, wildcard mistakes, or absent Access-Control-Allow-Origin. When debugging HTML pages rather than APIs, keep outbound integrity in mind too—our broken link checker helps ensure referenced assets actually return success codes.

Crawling, robots, and header-level indexing hints

Search engines may honor robots directives delivered as headers, not just meta tags. If you recently migrated hosts or added edge middleware, double-check that you are not accidentally emitting noindex via x-robots-tag. Likewise, confirm that staging environments are not publicly reachable with permissive caching headers that leak pre-production content. For robots.txt specifics, use the robots.txt checker and then validate individual URLs here to see how the edge actually responds.

Related free website and URL tools

Browse the full collection from our website and URL tools section, or jump straight to adjacent checkers below. For quick status validation without the full header table, the response code checker answers whether a URL returns 200, 301, 404, or errors in one step.

  • Broken Link Checker — Scan outbound links from any URL for 404s and broken hrefs—paste a page and audit links in seconds.
  • Redirect Chain Checker — Trace the full redirect path to the final URL and spot unnecessary hops hurting SEO and performance.
  • SSL Certificate Checker — Verify TLS certificate validity, expiry, issuer, and chain for any domain before users hit errors.
  • DNS Lookup Tool — Query A, AAAA, MX, CNAME, TXT, NS, and SOA records for troubleshooting email, hosting, and DNS.
  • WHOIS Lookup — Look up domain registration details: registrar, dates, and status for research and due diligence.
  • IP Address Lookup — Resolve IPv4 or IPv6 to geolocation, ISP, ASN, and hostname for network and fraud analysis.
  • Domain Age Checker — See how long a domain has been registered—useful for SEO trust signals and quick vetting.
  • Robots.txt Checker — Fetch and review robots.txt rules, directives, and sitemap lines to catch crawler misconfiguration.
  • Meta Tags Extractor — Extract title, meta description, Open Graph, Twitter Card, and canonical tags from any live URL.
  • Open Graph Preview — Preview how a link may appear when shared on social networks before you publish or pitch.

Frequently asked questions

What does this HTTP header checker do?
You enter a public http(s) URL. Our server requests that URL (following redirects safely), then returns the final HTTP status and a table of response header names and values—ideal for debugging cache, security, CORS, and content-type issues.
Does it follow redirects?
Yes. We resolve redirects up to a fixed hop limit and show headers from the final response, plus the final URL after hops. For a hop-by-hop trail, use our redirect chain checker alongside this tool.
Why might headers differ from my browser DevTools?
Servers often vary headers by user-agent, geography, cookies, HTTP version, and whether the request used GET versus HEAD. Some CDNs also send different cache directives to bots versus browsers. Treat this output as one real-world probe from our infrastructure.
Do you use GET or HEAD?
We try HEAD first to avoid downloading large bodies. If the origin rejects HEAD (for example 405 Method Not Allowed), we fall back to a minimal GET with a tiny Range request when supported.
Which security headers should I look for?
Common signals include Strict-Transport-Security (HSTS), Content-Security-Policy (CSP), X-Content-Type-Options, X-Frame-Options or frame-ancestors, Referrer-Policy, and Permissions-Policy. Presence and quality depend on your threat model—use this checker to verify what you actually emit in production.
Can I check headers for localhost or private IPs?
No. For safety, we only allow public http(s) URLs whose hostnames resolve to non-private addresses—similar to our other website probes.
How is this useful for SEO?
Headers influence crawling and indexing indirectly: canonical signals can appear as Link headers, x-robots-tag can affect indexing, redirects and cache headers affect freshness, and TLS/HSTS affect trust. Pair header review with our meta tag extractor and response code checker for a fuller on-page picture.
Will this expose secret cookies or tokens?
You only inspect headers returned to our unauthenticated server request. Do not paste URLs that embed secrets in query strings. If a site sets HttpOnly cookies, you may see Set-Cookie names at a high level—never share those values publicly.