HTTP Headers Viewer
View HTTP response headers for any URL
All response headers
Security header check
Response timing
Status code display
cURL export
JSON export
The API returns 200 OK. Your code handles it correctly. But the response takes 3 seconds when it should take 300ms. Is it the server? The network? Compression disabled? The answer is in the HTTP headers—if you can see them.
HTTP headers are the metadata of every web request: caching directives, security policies, content types, timing information. This viewer fetches and displays all headers from any URL, revealing how servers actually respond to requests.
What are HTTP Headers?
HTTP headers are key-value pairs sent with HTTP requests and responses. They contain metadata about the message: content type, caching rules, authentication requirements, security policies, and more. Headers control how browsers and servers communicate.
Common response headers:
Content-Type: application/json
Cache-Control: max-age=3600
Content-Encoding: gzip
Strict-Transport-Security: max-age=31536000
X-Content-Type-Options: nosniff
Whether content is cached, compressed, secure, or accessible—it's all determined by headers. Understanding them is essential for web development and security.
Why People Actually Need This Tool
Users never see HTTP headers, but headers determine security, performance, and functionality. A missing header can mean vulnerabilities or poor performance.
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Security auditing — Check for HTTPS, HSTS, CSP, and other security headers.
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Performance analysis — Verify compression, caching, and CDN headers.
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API debugging — Inspect response headers for rate limits, auth, and content type.
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SEO verification — Check canonical headers, redirects, and status codes.
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CORS troubleshooting — Debug cross-origin resource sharing issues.
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Cookie inspection — Analyze Set-Cookie headers for security flags.
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CDN configuration — Verify CDN headers like cache status and edge location.
How to Use the HTTP Headers Viewer
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Enter any URL — Website, API endpoint, or resource URL.
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Fetch headers — Tool makes a request and captures response headers.
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Review all headers — See every header returned by the server.
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Check security status — Identify missing or misconfigured security headers.
| Header Category | Example Headers | Purpose |
|---|---|---|
| Security | HSTS, CSP, X-Frame-Options | Protection against attacks |
| Caching | Cache-Control, ETag, Expires | Performance optimization |
| Content | Content-Type, Content-Encoding | Payload description |
| Authentication | WWW-Authenticate, Authorization | Access control |
| CORS | Access-Control-Allow-Origin | Cross-origin requests |
Missing security headers like HSTS, CSP, and X-Content-Type-Options leave sites vulnerable. Use this tool to audit your sites.
Real-World Use Cases
1. The Security Audit
Context: Preparing for penetration test. Need to review security posture.
Problem: Don't know what security headers are currently configured.
Solution: Check all production URLs for HSTS, CSP, X-Frame-Options, X-Content-Type-Options.
Outcome: Identify 3 missing security headers. Fix before pentest begins.
2. The Caching Mystery
Context: CDN bills are high. Content should be cached but seems to be fetched fresh.
Problem: Not sure if caching headers are configured correctly.
Solution: Check Cache-Control headers. Find no-store on static assets.
Outcome: Fix caching headers. CDN cache hit rate jumps from 10% to 85%.
3. The Compression Check
Context: Site speed test shows "Enable compression" warning.
Problem: Compression should be on. Need to verify.
Solution: Check Content-Encoding header. Missing—server not compressing.
Outcome: Enable gzip compression. Page weight drops 70%.
4. The CORS Debug Session
Context: Frontend getting CORS errors when calling API.
Problem: API should allow cross-origin requests. Error says otherwise.
Solution: Check Access-Control-Allow-Origin header. Missing entirely.
Outcome: Configure CORS on API. Frontend works correctly.
5. The API Rate Limit Investigation
Context: API calls failing with 429 Too Many Requests.
Problem: Need to know rate limit values and reset time.
Solution: Check X-RateLimit headers. See limit, remaining, and reset timestamp.
Outcome: Implement backoff strategy based on actual limits.
6. The Cookie Security Review
Context: Security team flagging cookies without Secure and HttpOnly flags.
Problem: Need to verify all cookies have proper security attributes.
Solution: Check Set-Cookie headers for Secure, HttpOnly, SameSite flags.
Outcome: Identify session cookie missing HttpOnly. Fix immediately.
7. The Redirect Chain Analysis
Context: Page loads slowly. Suspect multiple redirects.
Problem: Don't know if there's a redirect chain.
Solution: Follow Location headers through redirect chain.
Outcome: Find 4-hop redirect chain. Consolidate to single redirect. Page loads faster.
Common Mistakes and How to Avoid Them
Different environments (dev, staging, prod) may have different headers. Always check production.
Privacy and Data Handling
This HTTP Headers Viewer makes requests from your browser to fetch headers.
- Requests go directly to the target URL.
- No proxy or logging server involved.
- Results are not stored.
- Your inspection activity is not tracked.
Check any public URL—the request is between your browser and that server only.
Conclusion
HTTP headers are the control panel of the web. They determine security, performance, caching, and compatibility—yet they're invisible to normal browsing. You can't fix what you can't see.
This viewer makes headers visible. Check security configuration, debug caching issues, analyze API responses, and understand exactly how servers respond to your requests.
The web runs on headers. Make sure yours are configured correctly.