Security Headers Checker
LivePaste HTTP response headers and check for missing or misconfigured security headers.
# Get headers with curl: curl -I https://yourdomain.com # Or copy from DevTools: # Network tab → click any request → Response Headers
Understanding API & Web Development
HTTP security headers are the first line of defense for web application security. Missing or misconfigured headers leave applications vulnerable to clickjacking (missing X-Frame-Options), MIME sniffing attacks (missing X-Content-Type-Options), cross-site scripting (weak Content-Security-Policy), information leakage via Referer (missing Referrer-Policy), and downgrade attacks (missing HSTS). Security header audits are a standard part of penetration testing and compliance reviews.
Check any set of HTTP response headers for the presence and correct configuration of critical security headers: Strict-Transport-Security (HSTS), Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, Cross-Origin-Opener-Policy, and more. Each header is rated as Present, Misconfigured, or Missing with an explanation and recommended value.
The Devkitr Security Headers Checker analyzes a set of HTTP response headers you paste in and reports the status of each security header: Present and correctly configured, Present but misconfigured, or Missing — with explanations and recommended values for each.
In a typical development workflow, Security Headers Checker becomes valuable whenever you need to paste http response headers and check for missing or misconfigured security headers. Whether you are working on a personal side project, maintaining production applications for a company, or collaborating with a distributed team across time zones, having a reliable browser-based validation tool eliminates the need to install desktop software, write one-off scripts, or send data to third-party services that may log or retain your information. Since Security Headers Checker processes everything locally on your device, your data stays private and your workflow stays uninterrupted — open a browser tab, paste your input, get your result.
Key Features
8 Critical Headers Checked
Strict-Transport-Security, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, Cross-Origin-Opener-Policy, Cross-Origin-Resource-Policy.
Misconfiguration Detection
Detects common misconfigurations like HSTS without includeSubDomains, X-Frame-Options: ALLOW-ALL, and overly permissive CSP directives.
Recommended Values
Each missing or misconfigured header shows the recommended value with an explanation of why it matters.
Severity Ratings
Headers are rated High, Medium, and Low priority based on exploitation risk to help prioritize remediation.
How to Use Security Headers Checker
Get Response Headers
Use browser DevTools Network tab, curl -I https://yourdomain.com, or any HTTP client to get the response headers.
Paste Headers
Paste the raw response headers in the input area (e.g., the output of curl -I, or copy from DevTools).
Analyze
Click Analyze to parse and check each security header.
Review Results
See which headers are present, misconfigured, or missing, along with recommended values and remediation guidance.
Use Cases
Security Audit
Quickly audit any web application's response headers for the most critical security headers before a penetration test or compliance review.
DevOps Configuration Review
Verify that Nginx, Apache, or CDN configurations are correctly setting all required security headers after deployment.
Pre-Launch Checklist
Include security header validation in your launch checklist to ensure production deployments have baseline security headers configured.
Training
Demonstrate to developers which security headers their application is missing and explain what attacks each header prevents.
Pro Tips
Add security headers at the reverse proxy (Nginx/Caddy) or CDN layer rather than in application code — they apply to all responses including static assets.
Test in private/incognito mode or disable caching to see the actual current headers rather than cached responses.
Content-Security-Policy is the most impactful header for XSS prevention but also the most complex to configure correctly. Start with report-only mode.
Common Pitfalls
Setting X-Frame-Options: ALLOW-ALL thinking it allows specific origins
Fix: ALLOW-ALL is not a valid X-Frame-Options value in most browsers and behaves inconsistently. Use Content-Security-Policy: frame-ancestors for fine-grained control over which origins can embed your page.
Frequently Asked Questions
QWhich headers are checked?
HSTS, Content-Security-Policy, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, Cross-Origin-Opener-Policy, and Cross-Origin-Resource-Policy.
QHow do I get headers to paste?
Use browser DevTools (Network tab → select a request → Headers → Response Headers), curl -I, or any HTTP client.
QWhat is a misconfigured header?
A header that is present but uses an unsafe value — for example, X-Frame-Options: ALLOWALL or HSTS without the includeSubDomains directive.
Related Articles
Related Tools
URL Encoder/Decoder
Encode or decode URLs and query parameters for safe transmission.
User Agent Parser
Parse user agent strings to identify browser, OS, and device information.
DNS Lookup Tool
Query DNS records — A, AAAA, CNAME, MX, TXT, NS, and SOA records for any domain.
API Request Tester
Free online API tester — send HTTP requests and test REST APIs in your browser.