HTTP/2 Checker

About HTTP/2 Checker

HTTP/2 Checker tells you whether a site negotiates HTTP/2 by performing a TLS handshake and reading the application protocol the server selects. A yes means browsers can multiplex requests over one connection, which usually cuts load time for pages with many assets.

How to use it

1. Enter the domain, for example example.com, in the Domain box. A scheme or path is stripped.
2. Press Check HTTP/2. Our server connects on port 443 and offers h2 and http/1.1 through ALPN.
3. Read the banner: HTTP/2 supported in green, or HTTP/2 not supported in amber. The badge shows the protocol that was chosen.
4. Check the ALPN Protocol and TLS Version rows for the exact values the server returned.

When to use it

• Verifying that a reverse proxy or CDN change really turned HTTP/2 on.
• Finding out why a site still runs over HTTP/1.1 after a server upgrade.
• Comparing two hosting providers on protocol support before you choose one.
• Documenting protocol support as part of a performance audit.

Questions about HTTP/2 Checker

How does the check decide?

It offers h2 first and http/1.1 second during the TLS handshake. If the server answers h2, the result is supported. Anything else, including http/1.1 or no ALPN answer at all, counts as not supported.

Does it test HTTP/3?

No. HTTP/3 runs over QUIC on UDP, and this tool only performs a TCP and TLS handshake. A site can support HTTP/3 and still be reported here by its HTTP/2 result.

What do timeout and error mean in the protocol field?

They mean the handshake never completed. A timeout appears after 8 seconds without a response, and an error means the connection was refused or reset. Both are shown as a failed check with unsupported status.

Is the hostname sent to you?

Yes, because our server makes the connection. Only public hosts are allowed, and the connection is closed as soon as the handshake finishes without sending any request.

What is the request limit?

Around 20 checks per minute per visitor, which is generous for testing several domains one after another.

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