Free HTTP Header Checker

Analyze any website's HTTP response headers for security vulnerabilities, caching misconfigurations, SEO issues, and performance problems. Get a health score and actionable recommendations to improve your headers.

Why HTTP Headers Matter for SEO

HTTP response headers are invisible instructions from your server to browsers and search engine crawlers. While they're not visible on the page, they directly impact how search engines crawl, index, and rank your content. Misconfigured headers can prevent pages from being indexed, slow down your site, or expose security vulnerabilities — all of which hurt your SEO.

• Status codes tell search engines whether a page exists (200), has moved (301/302), or is broken (404/500)
• X-Robots-Tag can block indexing at the server level — even for non-HTML files like PDFs
• Cache-Control and related headers affect page speed, a confirmed Google ranking factor
• HSTS ensures your site always loads over HTTPS, which is required for ranking
• Content-Type with charset helps search engines correctly parse your content

How to Use This Tool

1. Enter a URL — Type or paste any website URL. The tool automatically adds https:// if missing.
2. Click "Check Headers" — The tool fetches the page and analyzes all response headers.
3. Review your score — See an overall health score based on how many checks pass, warn, or fail.
4. Fix issues by category — Each header is grouped into Security, Caching, SEO, or Performance with specific recommendations.
5. View raw headers — Expand the raw headers section to see every header returned by the server.

Common HTTP Header Issues

• Missing HSTS header: Without Strict-Transport-Security, browsers may attempt HTTP connections first, creating security risks and slowing page loads.
• No Content-Security-Policy: CSP is your primary defense against XSS attacks. Missing CSP leaves your site vulnerable to script injection.
• X-Robots-Tag set to noindex: This server-level directive blocks search engine indexing — often set accidentally during staging and forgotten in production.
• Missing compression: Without gzip or Brotli compression, your pages transfer at full size, significantly slowing page load times.
• Exposing server version: Detailed Server or X-Powered-By headers reveal your technology stack, making it easier for attackers to target known vulnerabilities.
• No Cache-Control: Without explicit caching directives, browsers and CDNs guess how to cache your content — often incorrectly.

Frequently Asked Questions

What are HTTP response headers?

HTTP response headers are metadata sent by a web server along with the requested content. They contain instructions for the browser about how to handle the response, including caching behavior, security policies, content type, and more. These headers are invisible to regular visitors but critical for security, SEO, and performance.

How do HTTP headers affect SEO?

HTTP headers directly impact SEO through status codes (200, 301, 404), the X-Robots-Tag header (which can block indexing), Content-Type and charset declarations, caching headers (which affect page speed), and HSTS (which ensures HTTPS). Misconfigured headers can prevent pages from being indexed or slow down your site.

What security headers should every website have?

Every website should have at minimum: Strict-Transport-Security (HSTS) to enforce HTTPS, X-Content-Type-Options set to "nosniff" to prevent MIME sniffing, Content-Security-Policy to prevent XSS attacks, X-Frame-Options or CSP frame-ancestors to prevent clickjacking, and Referrer-Policy to control referrer information.

What is the X-Robots-Tag header?

The X-Robots-Tag is an HTTP header that works like a meta robots tag but at the server level. It can instruct search engines to noindex, nofollow, or apply other directives to any type of file — including PDFs, images, and other non-HTML resources that cannot contain meta tags. This makes it especially useful for controlling indexing of non-HTML content.

What's the difference between Cache-Control and Expires headers?

Both control browser caching, but Cache-Control is the modern standard. Cache-Control uses relative time (max-age in seconds) while Expires uses an absolute date. When both are present, Cache-Control takes priority. For modern websites, Cache-Control is sufficient and the Expires header is optional.