HTTP/2 Support Checker

HTTP/2 Support Checker connects over TLS and checks which protocol the server actually negotiates through ALPN, the same negotiation a browser performs before sending its first real request.

Use this to confirm a server or CDN change actually enabled HTTP/2 the way you expect, or when investigating a performance difference between two servers and wanting to rule out protocol version as the cause.

This checks HTTP/2 specifically. HTTP/3 uses an entirely different transport (QUIC over UDP rather than TCP) that this check does not attempt to negotiate, so a server can support HTTP/3 or not independently of what this tool reports.