HTTP Headers Checker
Inspect HTTP response headers for any URL. Highlights security headers, cache policy, CORS and performance headers. Calculates a security grade.
Common Security Headers Guide
max-age=31536000; includeSubDomainsDENY or SAMEORIGIN.nosniff.strict-origin-when-cross-origin is a safe default.require-corp.same-origin for security.What is HTTP Headers Checker?
An HTTP headers checker is a web diagnostic tool that fetches the response headers returned by any publicly accessible URL and displays them in a clear, categorised view. HTTP response headers carry critical metadata about the server, content type, caching behaviour, security policies, and CORS rules that control how browsers interpret and display web resources.
Understanding your headers is fundamental to both performance optimisation and security hardening. Missing security headers such as 'Content-Security-Policy', 'Strict-Transport-Security', and 'X-Content-Type-Options' leave applications exposed to common attacks including XSS, clickjacking, and MIME-sniffing. Misconfigured CORS headers cause legitimate API requests to fail in browsers, while overly permissive CORS policies can expose APIs to cross-origin abuse.
This tool fetches the headers for any URL you enter, then organises the results into categories: general headers, security headers, caching headers, and CORS headers. A security score highlights which best-practice headers are present and which are missing, with a brief explanation of each finding. Cache-Control and Expires headers are parsed and explained in plain English so you can quickly understand your CDN and browser caching strategy. The raw header dump is always available for copying into documentation or bug reports.
How to Use HTTP Headers Checker
- Enter a URL
Type or paste any fully qualified URL (including https://) into the input field.
- Fetch headers
Click "Check Headers" to send a request and retrieve the HTTP response headers from the target server.
- Browse categorised results
Review headers grouped into security, caching, CORS, and general categories with plain-English explanations.
- Review the security score
See which critical security headers are present or missing and learn what each one protects against.
Key Benefits
Instantly see which security headers are missing and understand the risk each gap poses to your application.
Understand your cross-origin policy at a glance — spot overly permissive origins or missing preflight headers.
Cache-Control and Expires values are parsed into plain English so you know exactly how browsers and CDNs will cache the response.
Copy the complete raw header block for use in documentation, support tickets, or further analysis.
Frequently Asked Questions
HTTP response headers are metadata lines returned by a web server alongside the requested content. They instruct the browser on how to handle the content, security rules, caching, and more.
Content-Security-Policy (CSP) tells the browser which sources are allowed to load scripts, styles, and images. A strong CSP prevents cross-site scripting (XSS) attacks from running malicious code.
CORS (Cross-Origin Resource Sharing) is a browser security mechanism controlled by the Access-Control-Allow-Origin header. It determines which external domains can make requests to your API or resource.
No, the tool fetches headers from publicly accessible URLs only. For local development servers, use your browser's DevTools Network tab or a command-line tool like curl.