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HTTP/2 & HTTP/3 Checker

Check which HTTP protocol versions a website supports: HTTP/1.1, HTTP/2 and HTTP/3 (QUIC).

What are HTTP/2 and HTTP/3?

HTTP/2 and HTTP/3 are newer versions of the protocol browsers use to download web pages. They load many files in parallel over one connection, and HTTP/3 runs over QUIC for faster, more reliable connections on mobile networks.

What the checker tests

  • Negotiated protocol — the version the server actually uses when a client offers HTTP/2.
  • HTTP/2 support — required for multiplexing (many requests on one connection).
  • HTTP/3 advertisement — servers announce HTTP/3 through the Alt-Svc header (for example h3=":443"); browsers then switch to QUIC on later requests.

Why it matters

With HTTP/1.1, browsers open several connections and queue requests. HTTP/2 removes that bottleneck, which helps pages with many images, scripts and styles. HTTP/3 also avoids delays when packets are lost, which is common on mobile connections.

How to enable

Most modern servers (nginx, Apache with mod_http2, LiteSpeed, Caddy) and every major CDN support HTTP/2 over HTTPS. HTTP/3 is available on Cloudflare, Fastly, Caddy, LiteSpeed and recent nginx builds.

Frequently asked questions

Does HTTP/2 need HTTPS?

Browsers only use HTTP/2 over HTTPS, so in practice yes.

How do I know if HTTP/3 works?

If the Alt-Svc header advertises h3, browsers that support it will try QUIC on later requests. Your browser developer tools show the protocol used for each request.

Is HTTP/2 a ranking factor?

Not directly, but it helps page speed, which affects user experience and Core Web Vitals.