What This Tool Checks
HeaderCheckr follows safe redirects, checks the final URL, and reports the protocol it can verify from the live response.
Web Debugging
HTTP Protocol Checker
Check whether a site is using HTTP/1.1, HTTP/2, or advertising HTTP/3.
Guide
HTTP Protocol Checks
The HTTP protocol version affects connection reuse, page delivery, and how browsers talk to your CDN or origin server.
Use this tool to confirm whether the final URL is using a modern protocol path or still falling back to older HTTP behavior.
Why It Matters
HTTP/2 and HTTP/3 can improve performance for modern sites, especially when many assets are loaded over the same secure connection.
Protocol support is usually configured at the CDN, load balancer, or hosting layer, so it is worth checking after infrastructure changes.
Related Tools
After checking protocol support, run the Security Headers Checker to confirm browser security headers on the same final response.
FAQ
Is HTTP/2 always better than HTTP/1.1?
Usually for modern HTTPS sites, yes. HTTP/2 improves multiplexing and connection reuse, though the real impact depends on hosting, CDN, and asset delivery.
Can HeaderCheckr fully test HTTP/3?
It reports HTTP/3 when the final response advertises h3 through Alt-Svc. Direct QUIC negotiation is not performed by this lightweight checker.
Why does the final URL matter?
Protocol support can differ after redirects. The final response is the one browsers actually use after the redirect chain completes.