HTTP Header Viewer

HTTP Header Viewer - Check and Analyze HTTP Headers Online

A powerful online HTTP header viewer tool that displays HTTP request and response headers from any URL. See status codes, content types, cookies, cache headers, CORS headers, and more. Perfect for developers, testers, and anyone debugging web requests or APIs.

What are HTTP Headers?

HTTP headers are metadata sent between a client (browser) and server in HTTP requests and responses. They contain important information about:

- Request details (browser type, accepted formats, authentication)
- Response details (content type, caching rules, cookies)
- Security policies (CORS, CSP, X-Frame-Options)
- Content encoding and compression
- Connection management

Headers are essential for proper web communication and affect how browsers handle content.

How do I use this HTTP Header Viewer?

Using the tool is straightforward:

1. View your current request headers in the 'Your Request Headers' section
2. To check a URL's headers, enter it in the URL field
3. Click 'Check Headers' to fetch the response headers
4. Review the status code, headers, and values

Note: Due to CORS (Cross-Origin Resource Sharing) restrictions, some websites may block header requests from browsers. This is normal security behavior.

What are Request Headers?

Request headers are sent by the browser to the server and include:

- User-Agent: Browser and OS information
- Accept: Content types the browser can handle
- Accept-Language: Preferred languages
- Accept-Encoding: Compression methods supported
- Cookie: Stored cookies for the domain
- Referer: Previous page URL
- Authorization: Authentication credentials

These headers help servers understand the client's capabilities and preferences.

What are Response Headers?

Response headers are sent by the server and include:

- Status Code: Result of the request (200 OK, 404 Not Found, etc.)
- Content-Type: Type of content being returned
- Content-Length: Size of the response body
- Set-Cookie: Cookies to store
- Cache-Control: Caching instructions
- Access-Control-*: CORS permissions
- Server: Web server software

Response headers tell the browser how to handle the received content.

What does CORS error mean?

CORS (Cross-Origin Resource Sharing) is a security mechanism that prevents browsers from making requests to domains other than the one serving the page. When you see a CORS error:

- The target server doesn't allow cross-origin requests
- This is intentional security behavior
- It's not a problem with this tool or your browser
- Many websites block CORS for security

To work around CORS:
- Use browser extensions that disable CORS (for testing only)
- Test URLs that have CORS enabled
- Use server-side tools for production testing
- Check the actual website's headers using browser DevTools (F12 → Network tab)

Is my data safe?

Yes, your data is completely safe:

- All header checking happens in your browser
- Your request headers are read from the browser itself
- When checking URLs, requests go directly from your browser to that URL
- No data is sent to our servers
- No logging or tracking of URLs you check
- Works offline for viewing your own headers

The tool is completely client-side, ensuring your privacy.

Key Features

• View your current HTTP request headers
• Check response headers from any URL
• Display HTTP status codes
• Show all header key-value pairs
• Analyze CORS headers
• Check cache headers
• View cookies and authentication headers
• Dark mode support
• 100% client-side processing - data never leaves your browser
• No registration required
• Works with any HTTP/HTTPS URL
• Clean, easy-to-read header display
• Copy headers to clipboard
• Mobile-friendly responsive design