Free HTTP Headers Analyzer: Check Website Security & Performance
Analyze HTTP response headers for any website to check security headers, caching policies, server information, and web performance optimization. Professional header analysis tool for developers and security auditors.
What are HTTP Headers?
HTTP headers are metadata fields included in HTTP requests and responses that provide essential information about the operation of web servers and clients. These headers control caching behavior, security policies, content types, and server configurations that directly impact website performance, security, and user experience.
Our free HTTP headers analyzer examines any website's response headers to reveal security configurations, caching strategies, server technologies, and potential vulnerabilities. This information is crucial for web developers, security professionals, and SEO specialists optimizing website performance and security compliance.
Essential Security Headers
Security headers protect websites from common attack vectors including cross-site scripting (XSS), clickjacking, and man-in-the-middle attacks. Modern web security requires proper implementation of these critical HTTP headers:
Content-Security-Policy (CSP)
Purpose: Prevents XSS attacks by controlling resource loading
- • Specifies trusted content sources
- • Blocks malicious script injection
- • Prevents data exfiltration attacks
- • Enables violation reporting
Strict-Transport-Security (HSTS)
Purpose: Enforces HTTPS connections for enhanced security
- • Prevents protocol downgrade attacks
- • Forces HTTPS for specified duration
- • Includes subdomains in protection
- • Enables HSTS preload lists
Critical Security Headers Checklist
| Header Name | Security Protection | Implementation Priority |
|---|---|---|
| X-Frame-Options | Prevents clickjacking attacks | Critical |
| X-Content-Type-Options | Prevents MIME-type sniffing | Critical |
| Referrer-Policy | Controls referrer information leakage | High |
| Permissions-Policy | Controls browser feature access | Medium |
HTTP Caching Headers Analysis
Caching headers control how browsers and proxy servers store and serve cached content, directly impacting website performance, bandwidth usage, and user experience. Proper cache configuration reduces server load and improves page load speeds significantly.
Key Caching Headers
Cache-Control
Controls caching behavior for browsers and proxies with granular directives
- max-age: Specifies cache lifetime in seconds
- no-cache: Forces revalidation with server
- no-store: Prevents any caching of content
- private/public: Controls cache sharing permissions
ETag
Unique identifier for cached resources enabling conditional requests and efficient cache validation
Last-Modified
Timestamp indicating when the resource was last modified, used for cache validation
Server Information Headers
Server headers reveal information about the web server software, hosting infrastructure, and backend technologies. While useful for debugging, excessive server information can expose security vulnerabilities to attackers.
Common Server Headers
Security Considerations
- Server: Reveals web server software and version numbers
- X-Powered-By: Exposes backend frameworks and technologies
- X-AspNet-Version: Shows specific ASP.NET framework versions
- X-Generator: Reveals content management system details
Recommendation: Remove or minimize server information headers to reduce attack surface area
Content and CORS Headers
Content Headers
Content headers describe the payload characteristics including media type, encoding, language, and size. These headers ensure proper content interpretation by browsers and client applications.
- Content-Type: Specifies MIME type (text/html, application/json)
- Content-Length: Indicates response body size in bytes
- Content-Encoding: Describes compression method (gzip, deflate)
- Content-Language: Specifies natural language of content
Cross-Origin Resource Sharing (CORS)
CORS headers control cross-origin requests, enabling secure resource sharing between different domains while preventing unauthorized access to sensitive data.
Permissive CORS
- • Access-Control-Allow-Origin: *
- • Access-Control-Allow-Methods: GET, POST, PUT
- • Access-Control-Allow-Headers: Content-Type
- • Suitable for public APIs
Restrictive CORS
- • Specific origin domains only
- • Limited HTTP methods
- • Credential handling controls
- • Enhanced security for sensitive data
HTTP Headers Best Practices
Security Header Implementation
Implementing comprehensive security headers requires careful planning and testing. Start with non-breaking headers and gradually implement stricter policies:
- Assessment Phase: Use header analysis tools to audit current configurations
- Policy Development: Create security policies matching your application requirements
- Testing Environment: Implement headers in staging environment first
- Gradual Deployment: Roll out headers incrementally with monitoring
- Monitoring: Track violation reports and adjust policies as needed
Performance Optimization
Optimize HTTP headers for better performance while maintaining security and functionality:
- Minimize header size: Remove unnecessary headers to reduce bandwidth
- Optimize caching: Set appropriate cache lifetimes for different content types
- Enable compression: Use Content-Encoding for text-based resources
- Implement HTTP/2: Leverage header compression and multiplexing
Common HTTP Response Headers Reference
Based on analysis of top websites, here are the most frequently encountered HTTP response headers and their primary functions:
| Header | Usage % | Primary Function |
|---|---|---|
| Content-Type | 83.4% | Specifies media type of response |
| Date | 83.3% | Response timestamp |
| Server | 78.7% | Server software information |
| Set-Cookie | 75.3% | Session and tracking cookies |
| Cache-Control | 51.9% | Caching behavior control |
HTTP Header Security Testing
Security Assessment Methodology
Regular security header analysis helps identify vulnerabilities and compliance gaps. Follow this systematic approach:
Security Testing Checklist
- ✓ Missing Security Headers: Identify absent critical security headers
- ✓ Header Configuration: Verify proper header values and directives
- ✓ Information Disclosure: Check for excessive server information exposure
- ✓ HTTPS Enforcement: Validate HSTS and secure cookie configurations
Advanced Header Analysis
CDN and Proxy Headers
Content Delivery Networks and reverse proxies add specialized headers for caching, routing, and performance optimization:
- CF-RAY: CloudFlare request identifier for debugging
- X-Cache: Cache hit/miss status from CDN
- X-Amz-Cf-Pop: Amazon CloudFront edge location
- Via: Proxy chain information
- X-Varnish: Varnish cache request identifiers
Performance Monitoring Headers
Modern web applications use specialized headers for performance monitoring and optimization tracking, including Server-Timing for detailed performance metrics and X-Runtime for application response times.