HTTP Header Checker
An HTTP header checker reads the response headers a server sends alongside a page — the part that controls security policy and caching, invisible in the rendered page itself. Enter any URL to see its full response headers, plus plain-English findings on what's missing.
1 Enter a URL
Checking headers requires a server-side request — the target site sees Frost Rank's server, not your IP. Nothing checked is stored or logged.
2 Response headers
What response headers actually tell you
The HTML a page renders is only half the response — the headers sent alongside it control security policy, caching behavior, content type, and more, none of which shows up by looking at the page itself. A missing Content-Security-Policy or Strict-Transport-Security header won't make a site look broken; it just means those protections aren't being enforced by the browser.
Headers are also where caching gets decided. A response with no Cache-Control, or one set far too conservatively, means browsers and CDNs re-fetch content more than they need to — a quiet performance cost that compounds across every repeat visit and every crawl. Caching is just one line item on the broader Page Speed Checklist — worth checking if headers turn up more than one finding here.
For example, a typical finding looks like:
⚠️ Missing Strict-Transport-Security (HSTS) Tells browsers to always use HTTPS for this site, even if a link or bookmark points to http://.
How to use this tool
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1
Enter a URL
Paste the full address of the page, file or endpoint you want to inspect.
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2
Run the check
Click "Check headers". Our server requests that exact URL and does not follow redirects, so you see the response for the address you entered.
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3
Review the headers
Every response header is listed with its value, alongside the status code.
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4
Read the findings
The tool flags missing security headers (HSTS, Content-Security-Policy, X-Content-Type-Options, X-Frame-Options, Referrer-Policy), a missing Cache-Control, and Server or X-Powered-By values that reveal version details.
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5
Copy the headers
Click "Copy headers" to keep a record or share them with a developer or hosting provider.
Common use cases
- Taking a quick security baseline before a client handover or a penetration test.
- Confirming that a server, CDN or plugin change to caching or compression actually took effect.
- Checking the status code and Content-Type a crawler receives for a page, feed or sitemap.
- Spotting an
X-Robots-Tag: noindexheader in the list, which hides a page from search even when the HTML looks fine. - Comparing the header setup of a staging site with production.
Tips and common mistakes
- Check the final URL. If the address redirects, you are seeing the redirect's headers, not the page's. Find the destination first with the Redirect Chain Checker.
- Roll out a Content-Security-Policy gradually. Start with
Content-Security-Policy-Report-Onlyto see what it would block before enforcing it, or it may break scripts on live pages. - Enable HSTS only when HTTPS works everywhere. Browsers refuse plain HTTP for the whole max-age period, including on any subdomains you include.
- Cache files, not pages. Long cache lifetimes suit versioned files such as
app.3f9a.css; HTML usually needs a short lifetime so updates reach visitors. The HTTP security headers guide gives recommended values for each header.
Frequently asked questions
Security headers — like Content-Security-Policy, X-Content-Type-Options and Strict-Transport-Security — tell the browser to enforce protections a page can't guarantee on its own, like blocking mixed content or refusing to be embedded in a frame. Missing them doesn't mean a site is broken; it's one of the most common findings in a technical audit.
No — it shows the headers for the exact URL you enter. If that URL redirects, the Location header and status code will show it, but for the full hop-by-hop chain use Frost Rank's Redirect Chain Checker instead.
Cache-Control tells browsers and CDNs how long a response can be reused before checking back with the server. Missing or overly conservative caching means slower repeat visits and more load on your server — both of which factor into Core Web Vitals and how efficiently a site gets crawled.
It's not required, but many teams strip or generalize them since they reveal exact software and version details that make it slightly easier to target known vulnerabilities. It's a minor hardening step, not a critical fix.
Yes, completely free with no signup. The URL you check is sent to Frost Rank's server to read its headers — that's required for this tool to work — but it isn't stored or logged.
Flags the same security and caching headers checked during a real technical SEO audit — Content-Security-Policy, HSTS, X-Content-Type-Options, Cache-Control — not a generic pass/fail score.
Was this tool helpful?
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