📖 What is HTTP Header Analyzer?
HTTP Header Analyzer fetches the headers from any URL and displays them in a readable format. It highlights security headers (CSP, HSTS, X-Frame-Options), caching directives, CORS headers and content type. Use it to audit your site's security posture, debug caching issues, or verify API response headers. Everything runs in your browser.
💡 Example
Input
https://example.com
Output
Content-Type: text/html; charset=UTF-8
Strict-Transport-Security: max-age=31536000
X-Frame-Options: DENY
Cache-Control: public, max-age=3600
🛠️ Common Use Cases
- Auditing security headers (CSP, HSTS, X-Frame-Options) on your website
- Debugging caching issues (Cache-Control, ETag, Expires)
- Checking CORS headers for API integration
- Verifying Content-Type and encoding for API responses
- Inspecting redirect chains and status codes
📝 Essential Security Headers
Strict-Transport-Security — enforces HTTPS connectionsContent-Security-Policy — controls which resources can loadX-Frame-Options — prevents clickjacking (DENY or SAMEORIGIN)X-Content-Type-Options — prevents MIME type sniffing (nosniff)Referrer-Policy — controls referer header information
⚠️ Common Mistakes
- Missing HSTS — without Strict-Transport-Security, users can be downgraded to HTTP
- Overly permissive CSP —
unsafe-inline and unsafe-eval weaken Content-Security-Policy significantly - No-cache confusion —
no-cache means "revalidate before using," not "never cache." Use no-store to prevent caching entirely.
❓ Frequently Asked Questions
What are the most important security headers? ▾
Strict-Transport-Security (HSTS), Content-Security-Policy (CSP), X-Frame-Options, X-Content-Type-Options and Referrer-Policy are the essential five.
What does Cache-Control: no-cache mean? ▾
It means the browser must revalidate the cached version with the server before using it. It does NOT mean "don't cache." Use no-store for that.
How do I add security headers to my site? ▾
Add them in your web server config (Nginx, Apache), CDN settings (Cloudflare), or application middleware. Each header is a single line in the response.
Is my data private? ▾
Yes — all processing runs entirely in your browser. Your data is never sent to any server.
Is this tool free? ▾
Completely free — no login, no usage limits, works offline once loaded.
Yes — completely free, no login required, no usage limits.
Is my data private? ▾
Yes — all processing runs in your browser. Your data is never sent to any server.
Does it work offline? ▾
Yes — once the page is loaded, the tool works without an internet connection.