HTTP Headers Checker
Inspect any URL's HTTP response headers and security header configuration.
What are HTTP security headers?
Every time a browser loads a page, the server sends back HTTP response headers alongside the content. Most of these headers handle caching, content type, and connection details. A subset — security headers — tells the browser how to behave when it comes to cross-origin requests, content embedding, and transport encryption. Headers like Strict-Transport-Security, Content-Security-Policy, and X-Frame-Options act as instructions that limit what attackers can do even if they find a vulnerability in your application code. Without them, browsers fall back to permissive defaults that leave users exposed to clickjacking, MIME sniffing, and protocol downgrade attacks.
Why missing headers create real risk
A site can score well on performance benchmarks and pass an SSL certificate check while still missing critical security headers. The gap is common because headers are configured at the server or CDN level, not in application code, and they rarely break anything visible when absent. That makes them easy to forget after a migration, load balancer change, or CDN swap. Our checker audits six headers that security teams and scanning tools flag most often: HSTS, CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy. Each one gets a clear present or missing result so you know exactly what to fix. Pair it with our HTTP status checker to confirm your redirects and status codes are also correct.
From one-time check to continuous monitoring
Running a manual header check catches problems at a single point in time. Configuration drift, deploys, and infrastructure changes can remove headers without warning days later. If your site handles user data or sits behind compliance requirements, a missing HSTS header at the wrong moment is more than a best-practice gap — it is an incident. WatchCron's uptime monitoring watches your endpoints around the clock and alerts your team over Slack, email, or SMS when something changes. Use this free tool to audit your headers now, then set up monitoring to make sure they stay in place.