HTTP Header Analyzer - Analyze HTTP Headers Online

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HTTP Headers

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What are HTTP Headers?

HTTP headers are key-value pairs sent between clients and servers in HTTP requests and responses. Headers provide metadata about the request or response, including content type, caching directives, security policies, authentication credentials, and more. Understanding and properly configuring HTTP headers is crucial for web security, performance, and functionality.

Request headers are sent by the client (browser) to the server, containing information like accepted content types, cookies, and user agent. Response headers are sent by the server back to the client, including content type, caching rules, security policies, and server information.

Common HTTP Headers

Security Headers

Essential Security Headers

Security headers protect against common web vulnerabilities like XSS, clickjacking, and man-in-the-middle attacks. Implementing proper security headers is a critical part of web application security.

Recommended Security Headers: 
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Frame-Options: DENY
X-Content-Type-Options: nosniff
Content-Security-Policy: default-src 'self'
X-XSS-Protection: 1; mode=block
Referrer-Policy: strict-origin-when-cross-origin
Permissions-Policy: geolocation=(), microphone=()

Header Descriptions

  • Strict-Transport-Security (HSTS): Forces HTTPS connections
  • X-Frame-Options: Prevents clickjacking attacks
  • X-Content-Type-Options: Prevents MIME type sniffing
  • Content-Security-Policy (CSP): Controls resource loading
  • X-XSS-Protection: Enables browser XSS filtering
  • Referrer-Policy: Controls referrer information
  • Permissions-Policy: Controls browser features

Common Use Cases

1. Security Audit

Analyze response headers from your website to identify missing security headers. Check for HSTS, CSP, X-Frame-Options, and other security headers. Implement missing headers to improve security posture.

2. Caching Configuration

Review Cache-Control, Expires, and ETag headers to optimize caching strategy. Proper caching reduces server load and improves page load times for returning visitors.

3. CORS Troubleshooting

Analyze Access-Control-* headers when debugging cross-origin requests. Verify that CORS headers are correctly configured to allow legitimate cross-origin requests while blocking unauthorized access.

4. API Response Analysis

Examine API response headers to understand rate limiting, authentication requirements, and content negotiation. Headers like X-RateLimit-Remaining and X-Request-ID provide valuable debugging information.

5. Performance Optimization

Check compression headers (Content-Encoding), transfer encoding, and content length to optimize data transfer. Analyze timing headers to identify performance bottlenecks.

Header Examples

Example 1: Secure Website Headers

HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
X-Frame-Options: DENY
X-Content-Type-Options: nosniff
Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline'
Cache-Control: public, max-age=3600

Example 2: API Response Headers

HTTP/1.1 200 OK
Content-Type: application/json
X-RateLimit-Limit: 1000
X-RateLimit-Remaining: 999
X-RateLimit-Reset: 1640995200
Access-Control-Allow-Origin: https://example.com
Access-Control-Allow-Methods: GET, POST, PUT, DELETE

Example 3: Caching Headers

HTTP/1.1 200 OK
Cache-Control: public, max-age=31536000, immutable
ETag: "33a64df551425fcc55e4d42a148795d9f25f89d4"
Last-Modified: Wed, 21 Oct 2025 07:28:00 GMT
Expires: Thu, 31 Dec 2026 23:59:59 GMT

Example 4: Redirect Headers

HTTP/1.1 301 Moved Permanently
Location: https://www.example.com/new-page
Cache-Control: max-age=3600

Example 5: Authentication Headers

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example"
WWW-Authenticate: Basic realm="example"

Frequently Asked Questions

How do I view HTTP headers in my browser?
Open browser DevTools (F12), go to the Network tab, click on any request, and view the Headers section. You'll see both request and response headers.

Frequently Asked Questions

Yes, our Http Header Analyzer is completely free with no registration required. Use it unlimited times without any restrictions.

Yes, all processing happens locally in your browser. Your data never leaves your device and is not stored on our servers.

No installation needed. The tool works directly in your web browser on any device.

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