HTTP Headers
Fetch a Uniform Resource Locator (URL) and inspect response headers, status code, and redirect chain.
Security headers break silently. HSTS, CSP, and X-Frame-Options all need ongoing validation.
Monitor HTTP headers continuously
- ✓Header change detection
- ✓Security score tracking
- ✓HSTS / CSP / CORS monitoring
- ✓Email + Slack alerts
- ✓Historical diff view
- ✓SSL correlation
Frequently Asked Questions
What are HTTP response headers?
HyperText Transfer Protocol (HTTP) response headers are key-value pairs the server sends with every response, before the body. They tell the browser how to handle the content — caching policy, content type, security directives, cookies, redirects, and more. Inspecting them is the first step in debugging caching problems, Cross-Origin Resource Sharing (CORS) errors, and security issues.
What headers should every website have for security?
- Strict-Transport-Security — forces HyperText Transfer Protocol Secure (HTTPS).
- Content-Security-Policy — restricts what the browser can load.
- X-Frame-Options or Content Security Policy (CSP)
frame-ancestors— prevents clickjacking. - X-Content-Type-Options: nosniff — stops Multipurpose Internet Mail Extensions (MIME)-type sniffing.
- Referrer-Policy — controls how much referrer info is sent.
- Permissions-Policy — limits access to browser Application Programming Interfaces (APIs).
What does a redirect chain look like?
A redirect chain is a series of 301/302 responses before the browser reaches the final destination. For example: http:// → https:// → https://www. → final page. Each hop adds latency. Long chains (4+ hops) hurt performance and can cause Search Engine Optimization (SEO) issues; aim for a single redirect.
What is Cache-Control and how does it affect performance?
Cache-Control tells browsers and Content Delivery Networks (CDNs) how long to cache a response. max-age=86400 caches for 24 hours; no-store prevents caching entirely; must-revalidate requires a check with the server before serving a stale copy. Setting appropriate cache headers is one of the most impactful performance improvements for static assets.