Free HTTP Headers Checker

The HTTP Headers Checker is a free online tool that displays HTTP response headers from any URL, useful for debugging and security analysis.

Yes, it is completely free with no registration required.

HTTP headers reveal server type, caching policies, security configurations, content encoding, and other important technical details about a website.

Absolutely. The HTTP Headers Checker processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the HTTP Headers Checker is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the HTTP Headers Checker in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The HTTP Headers Checker works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

The checker scores seven response headers on a 100-point scale, then maps the total to a letter grade from A+ down to F. The two heaviest hitters are Strict-Transport-Security and Content-Security-Policy, each worth up to 25 points because they prevent protocol downgrade and cross-site scripting. X-Frame-Options adds 15 points for clickjacking protection, while X-Content-Type-Options, Referrer-Policy, and Permissions-Policy contribute 10 each. The legacy X-XSS-Protection header is worth a token 5 points. A site missing CSP and HSTS therefore loses half its possible score immediately, which is why those two are the first headers worth fixing. Enter a domain and the Security tab shows your grade plus exactly which headers are present, missing, or weakly configured.

They protect against entirely different attacks. Strict-Transport-Security (HSTS) tells the browser to always use HTTPS for a domain, blocking downgrade attacks and stripping; a strong value is max-age=31536000; includeSubDomains; preload, meaning one year, every subdomain, and eligibility for the browser preload list. Content-Security-Policy (CSP) instead controls where resources may load from — which script, style, image, and font sources the page trusts — and is one of the strongest defences against cross-site scripting and injection. HSTS hardens the connection; CSP hardens the page content. A well-secured site usually sets both, and both carry the full 25-point weight in the grade. This tool parses your CSP into individual directives and flags wildcards or unsafe-inline values, so paste a domain to see how each one is configured.

Cache-Control is a comma-separated list of directives that decide who may store a response and for how long. The word public means any cache, including a CDN, can hold it, while private restricts storage to the user's own browser. The max-age value is a lifetime in seconds, so max-age=86400 means one day. Directives like no-store forbid caching entirely, and no-cache permits storage but forces revalidation before reuse. Long lifetimes on static assets speed up repeat visits and lighten origin load, while HTML usually carries short or no-cache values so updates appear quickly. The Caching tab in this tool decodes these into plain language — public versus private, the max-age, and whether the response is cacheable at all — so enter a domain to see the policy explained without parsing the raw string yourself.

Browsers enforce the same-origin policy, which blocks JavaScript on one domain from reading the raw responses of another domain unless that server explicitly opts in with CORS headers. This is a deliberate security boundary: without it, any page you visit could silently probe your logged-in sessions on other sites. Because of that restriction, a purely in-browser tool cannot fetch live headers from an arbitrary third-party domain. This checker is built as a learning and demonstration tool — it generates representative, realistic header sets for the domain you enter so you can see exactly how grading, CSP parsing, and caching breakdown work. To inspect a live server's real headers, run curl -I https://example.com in a terminal, or open DevTools, switch to the Network tab, reload, and click the document request. Use the tool first to learn what good configurations look like.

These two short headers stop two common browser-side attacks. X-Frame-Options controls whether your pages can be embedded in an iframe by another site; setting it to DENY blocks all framing and SAMEORIGIN allows only your own domain, which defeats clickjacking, where an attacker overlays your page inside theirs to trick users into clicking hidden controls. X-Content-Type-Options has a single useful value, nosniff, which tells the browser to trust the Content-Type the server declared instead of guessing it from the bytes — preventing MIME-sniffing attacks where a file uploaded as an image is executed as a script. Both are quick wins worth 15 and 10 points respectively in this tool's security grade. Enter a domain and the Security tab shows whether each is present and correctly set, alongside the rest of the header analysis.