HTTP Header Checker
Analyze HTTP response headers for security, SEO, caching, and performance issues. Get actionable insights to optimize your server configuration.
Check HTTP Headers
Enter a URL to analyze its HTTP response headers
Health Scores
Enter a URL to see health scores
Security Headers Explained
Strict-Transport-Security (HSTS)
Forces browsers to use HTTPS, preventing downgrade attacks and cookie hijacking.
X-Content-Type-Options
Prevents browsers from MIME-sniffing, reducing risk of XSS attacks.
X-Frame-Options
Controls whether your page can be embedded in frames, preventing clickjacking.
Content-Security-Policy
Defines approved sources for content, preventing XSS and data injection attacks.
Referrer-Policy
Controls how much referrer information is sent when navigating away from your site.
SEO-Related Headers
X-Robots-Tag
HTTP alternative to meta robots tag. Controls indexing directives for non-HTML resources.
Link (canonical)
Specifies canonical URL via HTTP header - useful for PDFs and other non-HTML content.
Content-Type
Defines document type and character encoding. UTF-8 charset ensures proper rendering.
Content-Language
Indicates the language of the content, helping search engines serve relevant results.
Vary
Important when serving different content to mobile/desktop or for proper caching behavior.
Caching and Performance Headers Guide
Properly configured caching headers improve page load speed and reduce server load
Caching Headers
- Cache-Control
Primary header for controlling caching. Use max-age for static assets, no-store for sensitive data.
- ETag
Unique identifier for resource version. Enables efficient cache validation.
- Last-Modified
Timestamp of last modification. Helps browsers and crawlers determine freshness.
Performance Headers
- Content-Encoding
Indicates compression (gzip, br). Reduces transfer size by 60-80%.
- Connection: keep-alive
Reuses TCP connections, reducing latency for subsequent requests.
- Server-Timing
Provides backend timing metrics for performance debugging.
Common HTTP Header Issues and Fixes
Missing HSTS Header
Without HSTS, users can be vulnerable to SSL stripping attacks even if you redirect HTTP to HTTPS.
Strict-Transport-Security: max-age=31536000; includeSubDomains; preloadNo Compression Enabled
Uncompressed responses significantly increase load times. Enable gzip or Brotli compression.
Content-Encoding: gzip (or br for Brotli)Server Version Exposed
Exposing server version in headers helps attackers identify vulnerabilities.
Server: nginx (remove version number)Frequently Asked Questions
Why are HTTP headers important for SEO?
HTTP headers control how search engines crawl and index your content. Headers like X-Robots-Tag can prevent indexing, while caching headers affect crawl efficiency. Proper security headers also build trust with search engines. Run a Technical SEO Audit to analyze all SEO factors including headers.
What security headers should every website have?
At minimum: Strict-Transport-Security (HSTS), X-Content-Type-Options: nosniff, X-Frame-Options, and Content-Security-Policy. These protect against common web vulnerabilities.
How do caching headers affect Core Web Vitals?
Proper caching dramatically improves LCP (Largest Contentful Paint) for returning visitors. Well-cached resources don't need re-downloading, making pages load instantly.
Can HTTP headers override HTML meta tags?
In most cases, HTTP headers take precedence over HTML meta tags. For example, an X-Robots-Tag: noindex header will prevent indexing even if the HTML has a robots meta tag allowing indexing. The Link header can even set canonical URLs - check these with our Canonical URL Checker.
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