HTTP Headers

Inspect HTTP response headers for any URL. Analyze security headers (HSTS, CSP, X-Frame-Options), caching policies, and server information.

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APIPOST /api/v1/web/headers
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Try also: SSL Checker
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Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is HTTP Headers?

The HTTP headers inspector sends a request to any URL and displays every response header returned by the web server, organized by category and with clear indicators for security-critical headers. It highlights the presence or absence of essential security headers (Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy), shows caching directives (Cache-Control, ETag, Expires) that affect performance, identifies the server software and technology stack, and displays content encoding, CORS settings, and cookie attributes. HTTP response headers control how browsers handle your web pages — they dictate security policies, caching behavior, content rendering, and cross-origin access.

This free HTTP header checker is used by web developers verifying that server configurations are correct after deployment, security engineers auditing security header implementation, SEO specialists checking caching and compression headers for performance optimization, and DevOps teams debugging proxy, CDN, and load balancer header modifications.

How to Use

  1. 1Enter the full URL you want to inspect (e.g., https://example.com/page)
  2. 2Click 'Run Check' to send an HTTP request and retrieve all response headers
  3. 3Review security headers first: HSTS, CSP, X-Frame-Options, X-Content-Type-Options — missing ones are flagged
  4. 4Check caching headers: Cache-Control, ETag, and Expires — proper caching improves site speed significantly
  5. 5Note the Server header to identify the web server software and version
  6. 6Look for compression headers (Content-Encoding: gzip/br) to verify your server compresses responses

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

What are HTTP response headers and why do they matter?
HTTP response headers are metadata sent by a web server along with every page or resource it serves. They are invisible to regular visitors but control critical aspects of how browsers handle your content: security policies (preventing XSS, clickjacking, and other attacks), caching behavior (how long browsers store resources before re-fetching), content handling (character encoding, compression, MIME types), cross-origin access (which other websites can embed or fetch your resources), and cookie attributes (security flags like Secure, HttpOnly, SameSite). Misconfigured headers can create security vulnerabilities, degrade performance, or cause functional issues.
What security headers should my website have?
Every website should implement these security headers: Strict-Transport-Security (HSTS) — forces HTTPS connections, preventing protocol downgrade attacks. Content-Security-Policy (CSP) — defines which sources of content are allowed, preventing XSS and injection attacks. X-Frame-Options — prevents your pages from being embedded in iframes on malicious sites (clickjacking protection). X-Content-Type-Options: nosniff — stops browsers from guessing content types, preventing MIME confusion attacks. Referrer-Policy — controls how much URL information is sent with outgoing requests. Permissions-Policy — restricts which browser APIs (camera, geolocation, microphone) your site can use.
How do I check HTTP headers for my website?
Enter your website URL in the HTTP Headers tool and click Run Check. The tool sends an HTTP request to your server and displays every header in the response, organized by category with security headers highlighted. You can also check headers using browser DevTools (Network tab), but this tool provides a cleaner view with security analysis, works without visiting the site, and can check URLs that require specific access configurations.
What caching headers should I use for best performance?
For static assets (images, CSS, JavaScript with hashed filenames), set Cache-Control: public, max-age=31536000, immutable — this tells browsers to cache for 1 year since the hashed filename changes when content updates. For HTML pages, use Cache-Control: no-cache or max-age=0, must-revalidate — browsers should always check for a fresh version. For API responses, use Cache-Control: private, no-store if the data is user-specific. Always enable compression (Content-Encoding: gzip or br) — this reduces transfer size by 60-80% and is one of the biggest performance wins.
How do I add security headers to my website?
Security headers are configured in your web server or hosting platform. In Nginx, add headers in your server block with 'add_header' directives. In Apache, use the Header directive in .htaccess or httpd.conf. Most CDN providers (Cloudflare, AWS CloudFront, Vercel) offer header configuration through their dashboards or edge rules. Managed hosting platforms often have security header settings in their control panels. After adding headers, use this HTTP Headers checker to verify they appear correctly in the response — sometimes proxy servers or CDNs strip or modify headers.

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API Endpoint

POST /api/v1/web/headers
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