DNS
Resolvers can return different cached records depending on geography, TTL and propagation state.
Network & Web Tools
Pro diagnostic reportHTTP Headers Checker Online Free
Inspect response headers and review common web security headers for a public URL.
Diagnose
Run a bounded public check.
Understand
See a health score and explanation.
Act
Follow prioritized recommendations.
About this tool
HTTP response headers describe caching, content type, redirects, server behavior and browser security policies. This checker displays the headers returned by a public page and highlights several commonly reviewed security headers. Presence alone does not prove that a policy is correctly configured.
Common use cases
- ✓ Check Content-Security-Policy and HSTS deployment.
- ✓ Inspect cache-control and content-type behavior.
- ✓ Troubleshoot proxy, CDN or redirect configuration.
- ✓ Compare headers before and after a release.
How to use it
- Enter the public URL you want to inspect.
- Run the checker and review the complete header list.
- Check the highlighted security-header section.
- Validate policy values with your application and security requirements.
Important interpretation notes
- • Security headers must be configured correctly, not merely present.
- • A server may return different headers for authenticated sessions or other paths.
- • This is an informational check rather than a penetration test.
Professional interpretation guide
Understand and verify your http headers checker results
Use the result as a focused diagnostic signal. Verify important findings before changing DNS, hosting, security, caching or application configuration.
What the result tells you
- ✓ Response headers describe caching, content type, security controls and server behaviour.
- ✓ Status and final URL provide context for the header set.
- ✓ Missing headers are not automatically vulnerabilities; relevance depends on the application.
How to verify it
- Compare with browser developer tools.
- Test representative pages and API endpoints.
- Review CDN, reverse-proxy and application configurations together.
Network diagnostics
Interpret results in the correct protocol layer
Network tools observe different layers: DNS resolves names, TCP establishes connections, TLS authenticates encrypted sessions and HTTP carries requests, redirects, headers and caching rules. A successful result at one layer does not prove that the complete website or application is healthy.
TLS
Certificate validity, hostname matching, trust chains and protocol support are separate checks.
HTTP
Status codes, redirect chains, headers and caching directives describe application behaviour.
Measurement context
Latency and reachability vary by location, network path, browser and time.
What the operation can change
- A cached DNS answer may differ from an authoritative nameserver response.
- A 200 status code can still return the wrong content or an application error page.
- A valid certificate does not prove the website itself is trustworthy.
- Security-header tools report configuration, not complete vulnerability coverage.
Domain-specific verification
- Repeat tests from another network or resolver when location matters.
- Check the final URL and every redirect hop.
- Confirm timestamps, certificate names and expiry dates.
- Use browser developer tools and server logs for production incidents.
Common mistakes to avoid
- • Checking only the homepage.
- • Adding security headers without understanding compatibility.
- • Assuming server-identification headers are always accurate.
Privacy and safe use
The URL is requested to read public response headers. Do not submit private endpoints or URLs containing credentials.
Limitations
- • Headers can vary by route, method, region, cookies and authentication.
- • This tool does not perform a complete security audit.
Continue the diagnostic workflow
Combine related checks instead of relying on one isolated result.
Related Network & Web Tools
Frequently asked questions
What is Content-Security-Policy?
CSP restricts which resources a browser may load and can reduce some injection risks when configured carefully.
What is HSTS?
Strict-Transport-Security tells supporting browsers to prefer HTTPS for a defined period.
What does X-Content-Type-Options do?
The nosniff value reduces MIME type guessing in supported browsers.
Why are some headers missing?
They may not be configured for that path, proxy or environment.
Does every website need identical headers?
No. Policies should match the application, content and deployment model.
Does this tool change headers?
No. It only displays the headers returned to the server-side request.