HTTP Headers Explainer – Complete Header Reference
HTTP headers are metadata sent between clients and servers with every HTTP request and response. They control caching, authentication, content negotiation, CORS, security, and much more. Understanding HTTP headers is essential for web development, API design, and debugging. The HTTP Headers Explainer by ToolfolioHub provides a comprehensive, searchable reference of common HTTP headers with descriptions and examples.
Whether you're debugging API issues, configuring web servers, or learning web protocols, this tool helps you understand and use HTTP headers effectively.
What are HTTP Headers?
HTTP headers are key-value pairs sent with requests and responses:
- Request Headers: Sent by the client (browser) to the server
- Response Headers: Sent by the server back to the client
- Metadata: Provide information about the request/response, not the actual content
Headers control how browsers and servers handle requests and responses.
Header Categories
1. Content Headers
Control content type, encoding, and length:
- Content-Type: Media type (e.g., `application/json`, `text/html`)
- Content-Length: Size of the body in bytes
- Content-Encoding: Compression format (e.g., `gzip`, `deflate`)
2. Request Headers
Tell the server what the client accepts:
- Accept: Preferred media types for response
- Accept-Encoding: Preferred compression formats
- Accept-Language: Preferred languages
3. Security Headers
Protect against attacks:
- Authorization: Credentials for authentication
- X-Frame-Options: Prevents clickjacking
- Strict-Transport-Security: Forces HTTPS connections
4. CORS Headers
Control cross-origin resource sharing:
- Access-Control-Allow-Origin: Which origins can access resources
- Access-Control-Allow-Methods: Allowed HTTP methods
- Access-Control-Allow-Headers: Allowed request headers
5. Caching Headers
Control browser and proxy caching:
- Cache-Control: Caching directives
- ETag: Entity tag for cache validation
- If-None-Match: Conditional request using ETag
Common Use-Cases
- API Development: Set Content-Type, handle CORS, manage authentication
- Web Security: Configure security headers to prevent attacks
- Performance: Control caching and compression
- Debugging: Inspect headers to troubleshoot issues
Conclusion
The HTTP Headers Explainer is an essential reference for web developers working with HTTP protocols. With searchable headers, clear descriptions, and practical examples, it helps you understand and use headers effectively in your projects.