HTTP Headers Checker

HTTP Headers Checker — View Response Headers Online

The 101IP HTTP Headers Checker lets you view the full list of HTTP response headers for any website — directly from your browser, without tools or software installation.

What are HTTP response headers?

HTTP headers are metadata that the server sends with each response. They control caching, security, encoding, redirects, and much more. The key headers our tool shows:

• Server / X-Powered-By — web server type and backend technology;
• Content-Type / Content-Encoding — content type and compression method;
• Cache-Control / ETag — caching behavior;
• Strict-Transport-Security (HSTS) — forced HTTPS;
• X-Frame-Options — clickjacking protection;
• Content-Security-Policy (CSP) — script and resource loading policy;
• Access-Control-Allow-Origin (CORS) — cross-origin request policy;
• Set-Cookie — cookie settings;
• CF-Ray / CF-Cache-Status — Cloudflare CDN headers.

When is HTTP Headers Checker useful?

• checking security headers for a website audit;
• diagnosing caching issues and CDN configuration;
• verifying CORS settings for API integration;
• detecting web server and framework in use;
• checking redirect chains and final URLs.

Bookmark 101IP and use our free HTTP headers checker whenever you need to quickly inspect a website's response headers.

Frequently Asked Questions

• Why are security headers (HSTS, CSP) missing for my domain?

  Your domain URL may not be added to the HTTP settings on 101IP. In the settings, you can enable Strict-Transport-Security (HSTS) and Content-Security-Policy (CSP). If they are not enabled, the system will not add them, and the headers will not be sent.

• How do I properly configure Cache-Control for static files?

  Cache-Control is configured as follows: the no-cache directive forces the browser to check for updates on every request, while public, max-age=3600 enables caching for one hour. The optimal value depends on the file type and update frequency. For static resources, we recommend long-term caching.

• Can I add custom headers to enable CORS for my API?

  Yes, you can add custom headers in the URL settings (for example, https://api.example.com/endpoint). Specify the required headers: Access-Control-Allow-Origin, Access-Control-Allow-Methods, and others. For complex requests, you may also need to add preflight request headers.