Live diagnostic
HTTP Header Checker
Inspect any URL's response headers and audit key security and SEO headers. Free, no signup.
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Every response your server sends carries a set of HTTP headers that quietly shape security, caching, and how search engines treat the page. This checker reads the live headers for any URL — following redirects to the final response — and highlights the security and SEO headers that matter most, so you can see exactly what a visitor’s browser receives.
How it works
- 01
Enter a URL
Paste the address you want to inspect — a page, an API endpoint, or any reachable URL.
- 02
Read the response
Sitewell fetches the URL, follows redirects to the final response, and captures every header the server sent.
- 03
Spot the gaps
Review the full header list plus a checklist of key security and SEO headers, then fix anything missing.
Frequently asked questions
- What are HTTP response headers?
- HTTP response headers are metadata a server sends alongside a page — things like the content type, caching rules, the server software, and security directives. They control how browsers, caches, and crawlers treat your response, so the wrong (or missing) header can quietly hurt performance, security, or SEO.
- Which security headers should my site send?
- At a minimum, look for Strict-Transport-Security (HSTS), Content-Security-Policy, X-Content-Type-Options: nosniff, and X-Frame-Options (or a CSP frame-ancestors directive). This checker flags whether each of those is present so you can close the gaps.
- Why does cache-control matter for SEO and speed?
- Cache-Control tells browsers and CDNs how long they can reuse a response. Sensible caching cuts load time and server cost; missing or overly strict caching makes every visit slower. Crawlers also benefit from a fast, cacheable site.
- Does Sitewell follow redirects when reading headers?
- Yes. The checker follows the redirect chain to the final URL and reports the headers of that final response, so you see what a real visitor's browser ends up with rather than an intermediate 301.