Short answer. To check your site's headers, use the enterno.io online checker (shows all response headers, redirects and status codes), your browser's DevTools (Network tab), or the curl -I https://example.com command in a terminal. Online tools are handier for a one-off check and SEO audits; curl is better for scripts and CI.
What an HTTP header checker shows
HTTP headers are metadata that the server and browser exchange on every request. A header checker reveals exactly what your server returns in its response and helps you spot misconfigurations. Headers handle several jobs:
- Security — Content Security Policy, HSTS, X-Frame-Options, X-Content-Type-Options.
- Caching — настройка Cache-Control, ETag, Expires.
- Redirects and status — Location, codes 301/302/200/404 and redirect chains.
- Compression and content type — Content-Encoding (gzip/brotli), Content-Type.
For the basics, see our article on HTTP headers, and for decoding server responses, our guide to HTTP status codes.
Remember: the headers you see in the browser can differ from what the origin server returns. CDN, proxies and WAF (such as Cloudflare) add, strip or rewrite headers on the fly — so always check both the final response and the behavior across the entire redirect chain.
To pull just one header out of a response, combine curl with grep:
curl -sI https://example.com | grep -i content-securityThe -s flag hides the progress bar, -I requests headers only, and grep -i filters the line case-insensitively — handy when you want to confirm a specific policy is present without reading the whole response.
Header checker comparison
| Tool | Type | Cost | Redirects | Security grade | Best for |
|---|---|---|---|---|---|
| enterno.io | Online checker | Free (48+ tools) | Yes (full chain) | Yes (header grade) | SEO, audits, monitoring |
| SecurityHeaders.com | Online (security focus) | Free | Partial | Yes (A–F) | Security header checks |
| curl -I | CLI | Free | With -L flag | No (manual) | Scripts, CI/CD |
| Browser DevTools | Browser | Free | Yes | No | On-the-fly debugging |
| SSL/TLS проверку.io | Online | Free | Yes | No | Redirect analysis |
How to choose a header checker
Match the tool to your scenario:
- One-off check and SEO audit — the enterno.io online checker shows all headers, the redirect chain, the status code and grades your security headers in one report.
- Security headers only — SecurityHeaders.com gives a letter grade. For the full picture, see the security headers guide.
- Automation —
curl -I -Lin scripts or CI/CD checks headers on every deploy. enterno.io provides a REST API документацию and an MCP server for integration. - Real-time debugging — the Network tab in DevTools shows the headers of every request right in the browser.
What to look at first
A minimal checklist when inspecting your site's headers:
- The site returns 200 on key pages and proper 301s on old URLs.
- Key HTTP security headers are present: HSTS, CSP, X-Content-Type-Options.
- Compression is configured — Content-Encoding contains gzip or brotli.
- Static caching is set via Cache-Control.
- No unnecessary redirect chains (each extra hop slows the page down).
enterno.io offers 48+ free tools: an HTTP header checker, CSP/CORS/cookie analyzers, plus SSL and speed checks. The free plan includes 10 monitors with alerts via Telegram, Slack, email and webhook so you can track header and status-code changes continuously.
Unnecessary redirects are a silent enemy of performance and SEO. Every hop in the chain (for example http → https → www → final URL) adds a full round-trip to the server. Collapse the chain to a single 301 and always inspect the whole chain, not just the final page.
FAQ
How do I quickly check a site's headers?
The simplest way is to paste the URL into an online header checker: in a couple of seconds you see all response headers, the redirect chain and the status code. In a terminal, the equivalent is curl -I https://example.com.
Why is an online checker better than curl?
An online checker needs no terminal, follows redirects automatically, highlights problems visually and often grades security headers right away. curl is more convenient for scripts and automated CI checks.
Which headers matter most for SEO?
Correct status codes (200/301/404), no unnecessary redirects, and caching and compression headers. They affect indexing and speed, which search engines factor into ranking.
Can I automate header checks?
Yes. Use curl -I in a CI/CD pipeline or the REST API of a checking service. enterno.io provides an API and an MCP server so you can embed header checks into automated tests.