🛡️

HTTP Security Headers Analyzer

Paste your HTTP response headers to get an instant security grade and actionable recommendations for each header.

Tip: In Chrome DevTools → Network tab → click any request → Headers → copy the Response Headers section.

About HTTP Security Headers Analyzer — Security Headers Checker Online

HTTP security headers are server-sent directives that tell browsers how to handle your page's content — which scripts can run, whether the page can be framed, whether HTTPS is enforced, and what information gets shared with third parties. Missing or misconfigured security headers are one of the most common findings in web security audits, and fixing them doesn't require application code changes — most can be added in your web server configuration in a few minutes. This tool analyzes your response headers, assigns a letter grade based on coverage, and explains exactly what each missing header does and why it matters.

Web developers typically check security headers before launch and after major infrastructure changes. A page that served headers correctly on the old server may lose them after migrating to a CDN or load balancer if the new layer doesn't forward them. Security teams use header analysis as a first pass during audits — it's a quick, high-signal check. Bug bounty hunters commonly check security headers as part of their initial reconnaissance. And developers responding to a penetration test finding of "missing Content-Security-Policy" can use this tool to understand what a CSP does before deciding how to implement one.

How to Use HTTP Security Headers Analyzer

  1. Open Chrome DevTools by pressing F12, then click the Network tab and reload your page.
  2. Click the first document request in the list (the HTML page itself), then click the Headers tab in the right panel.
  3. Scroll to the Response Headers section and copy all the header lines (including the HTTP status line if present).
  4. Paste the copied headers into the text area above and click Analyze Headers.
  5. Review the grade, check which headers are present (green) and which are missing or misconfigured (red/orange), and use the explanations to prioritize which headers to add to your server configuration.

Security Headers Explained

Each security header protects against a specific class of attack — understanding what each one does determines how urgently you need to add it for your specific application.

  • Strict-Transport-Security (HSTS): Tells browsers to only connect to your site over HTTPS, even if the user types http:// or follows an HTTP link. Prevents protocol downgrade attacks and cookie hijacking on networks where an attacker can intercept HTTP traffic. The max-age value specifies how long the browser remembers this instruction — 31536000 (one year) is the standard. Without HSTS, users who visit your site over HTTP first are vulnerable on every visit until they upgrade.
  • Content-Security-Policy (CSP): The most powerful but most complex security header. CSP tells the browser exactly which script sources, stylesheet sources, image sources, and other resource types are allowed to load. A strict CSP prevents cross-site scripting (XSS) attacks by refusing to execute injected scripts even if they're present in the page. For most sites, adding even a basic CSP (blocking inline scripts and restricting external script sources) significantly reduces XSS risk.
  • X-Content-Type-Options: With the value nosniff, prevents browsers from guessing the content type of a response and overriding the declared Content-Type. Without this header, some browsers will execute JavaScript in a response even if the server declares it as text/plain — a technique used in some content injection attacks. This header has a single valid value and is trivial to add.
  • X-Frame-Options: Prevents your page from being embedded in an <iframe> on another site. Without this header, an attacker can load your page in an invisible iframe overlaid on their own page and trick users into clicking buttons they can't see (clickjacking). The DENY value blocks all framing; SAMEORIGIN allows framing only by your own domain. CSP's frame-ancestors directive is the modern replacement, but X-Frame-Options is still widely supported and useful as a fallback.
  • Referrer-Policy: Controls what URL information is sent in the Referer header when users navigate from your page to another site. Without a Referrer-Policy, the full URL (including query strings and URL parameters) is sent to external sites. strict-origin-when-cross-origin is the recommended value — it sends only the origin (not the path or query) to external sites while sending the full URL to same-origin requests.
  • Permissions-Policy: Controls which browser features and APIs the page can use — camera, microphone, geolocation, payment request, and others. Adding a restrictive Permissions-Policy prevents third-party scripts embedded in your page (analytics, ads, widgets) from requesting features your site doesn't use. A common baseline: camera=(), microphone=(), geolocation=() blocks all three unless your site explicitly needs them.

Tips for Improving Your Security Header Grade

Adding headers in the right order and understanding what each one costs in terms of implementation effort helps prioritize the work.

  • Start with the easy wins: X-Content-Type-Options (nosniff), X-Frame-Options (DENY or SAMEORIGIN), and Referrer-Policy are single-line additions to your server config with no application-level changes required. These three alone improve your score significantly and protect against real attack classes. Add them first.
  • Add HSTS only after confirming full HTTPS coverage: Once HSTS is set, browsers will refuse to connect over HTTP for the duration of max-age. If any part of your site still serves content over HTTP, enabling HSTS will break it. Confirm that all pages, assets, and subdomains are HTTPS-accessible before setting HSTS, and start with a short max-age (300 seconds) for testing before setting it to a year.
  • Build CSP incrementally using report-only mode: A strict CSP will break sites that rely on inline scripts and third-party resources. Use Content-Security-Policy-Report-Only first — it logs violations without blocking anything, letting you see what a strict policy would break before you enforce it. Build the policy from the report data, then switch to the enforcing header when the violations are resolved.
  • Check headers on all paths, not just the homepage: Security headers are typically set at the server or CDN layer and should apply uniformly — but some configurations add headers only to specific routes. Test the checkout page, API endpoints, and authenticated pages separately to confirm headers are present everywhere, not just the homepage that your initial test covered.

Why Use an HTTP Security Headers Analyzer Online

The alternative is reading the raw header output from curl or browser DevTools and manually comparing against a checklist of security headers. A tool that grades the result and explains each header's purpose and risk level is faster and more useful for sharing with stakeholders — a letter grade communicates the security posture more clearly than a list of header names to a non-technical manager or client.

Development teams doing a pre-launch security review benefit from catching missing headers before go-live rather than in a post-launch penetration test. Freelance developers doing a quick security check for clients benefit from the explanation text that helps communicate findings without requiring deep security knowledge. Security auditors benefit from a tool that works on any machine without installing curl or configuring tools — paste the headers from a screenshot or a text file and get the analysis instantly.

Frequently Asked Questions about HTTP Security Headers Analyzer

In Chrome: press F12 to open DevTools, click the Network tab, reload the page, click the first document request in the list (the HTML page), then click the Headers tab in the right panel. Scroll to Response Headers and copy all the lines. Alternatively, use curl from the terminal: curl -I https://yourdomain.com outputs the response headers directly. The Load Sample button in this tool shows what a well-configured header set looks like.

No. All analysis runs entirely in your browser using JavaScript. Your headers are never transmitted to any server. HTTP response headers contain no sensitive data — they're public information that any browser receives when requesting your page. There's no security concern with pasting them here.

A or B. An A grade indicates all major security headers are present and configured correctly. A B grade typically means one or two headers are missing or sub-optimally configured. C and below indicates significant gaps — specifically, likely missing HSTS, CSP, or X-Frame-Options. For most production sites, a B is the practical target; a full A with a strict CSP requires more implementation work but is appropriate for sites handling authentication or payments.

For Nginx, add headers in the server or location block using add_header HeaderName "value";. For Apache, use Header set HeaderName "value" in your .htaccess or VirtualHost config (requires mod_headers). For CDNs like Cloudflare, headers can be added via Transform Rules or Page Rules without touching the origin server. For Node.js/Express applications, use the Helmet middleware which sets sensible defaults for all major security headers automatically.

CSP requires you to enumerate every legitimate resource source your page uses — scripts, styles, fonts, images, API endpoints. Modern web pages often load resources from dozens of third-party domains (analytics, CDNs, ad networks, fonts), and a strict CSP blocks anything not explicitly allowed. Start with report-only mode using Content-Security-Policy-Report-Only to see what a policy would block before enforcing it. This makes CSP implementable without breaking the site, though it requires time to build the allowlist correctly.

Not meaningfully. Security headers are small text values added to HTTP responses — they add a few bytes per response with no processing overhead. HSTS and CSP can actually improve performance: HSTS eliminates the HTTP-to-HTTPS redirect on subsequent visits, and a strict CSP prevents browsers from loading unnecessary third-party resources. No security header adds measurable latency to page load times.