HTTP Header Checker
Check live response headers
Source Input
Processed Output
What is the HTTP Header Checker?
Response headers control security, caching, and how crawlers treat your pages. This checker fetches any URL live and analyzes the real headers it returns — grading security headers (HSTS, CSP, X-Frame-Options), explaining cache directives, auditing cookie flags, and listing exactly what's missing with the header you should add.
Frequently Asked Questions (FAQ)
Q: Do security headers affect SEO?
Indirectly but really: HTTPS is a ranking signal, and browsers flag insecure sites — which destroys click-through. HSTS and CSP also protect against hijacking that can inject spam into rankings.
Q: Why does my server return different headers than my origin?
CDNs and proxies (Cloudflare, Vercel) add and override headers. Always check the live edge response — that's what users and crawlers receive.
Key Features
- Fetches live response headers from any URL
- Security header grading (HSTS, CSP, XFO)
- Cookie flag auditing (Secure, HttpOnly, SameSite)
- Cache-Control explanation
- Server fingerprint disclosure warnings
How to Use the HTTP Header Checker
- 1Paste your input into the editor above — or start from the preloaded example.
- 2Adjust any options, then click Run to process instantly in your browser.
- 3Review the output panel, then copy, download, or save it as a reusable snippet.