HTTP Header Check
Analyze HTTP response headers – security headers, Cache-Control, CORS and more
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Analyze HTTP response headers – security headers, Cache-Control, CORS and more
Enter URL (with or without https://)
Get notified when new tools launch.
HTTP response headers are invisible metadata that every web server sends with every response. They control how browsers, CDNs and search engines process a page — from caching to security policies to CORS access rights.
Particularly relevant for security are security headers like
Strict-Transport-Security,
Content-Security-Policy
and
X-Frame-Options.
Many servers do not deliver these headers — a common security issue.
For SEO, the X-Robots-Tag header is relevant — it can block entire directories from search engines, even without access to the HTML. Additionally,
Cache-Control
directly affects load time and therefore Core Web Vitals.
HTTP response headers are metadata that a web server sends with every response. They control caching behavior, security policies, content types and CORS access rights. Browsers and search engines evaluate these headers to process the page correctly.
The most important security headers are: Strict-Transport-Security (HSTS) for enforcing HTTPS, Content-Security-Policy (CSP) against XSS attacks, X-Frame-Options against clickjacking, X-Content-Type-Options against MIME sniffing and Permissions-Policy for controlling browser features.
Cache-Control controls how long browsers and CDNs may cache a page or resource. Set correctly, it significantly reduces load times and server load. Key values are max-age (seconds), no-cache (always revalidate) and no-store (never cache).
CORS (Cross-Origin Resource Sharing) defines which external domains are allowed to access resources on your server. It is relevant for APIs, fonts and assets embedded from other domains. The Access-Control-Allow-Origin header controls the permitted origins.
Yes. The X-Robots-Tag header can block pages from search engines — similar to the meta robots tag, but also for non-HTML files like PDFs. Cache-Control affects load speed and therefore Core Web Vitals. HSTS signals to Google that the site permanently uses HTTPS.