HTTP/2 & HTTP/3 Checker
Check whether a server supports HTTP/2 and advertises HTTP/3.
About the HTTP/2 & HTTP/3 Checker
HTTP/1.1 can only send one request at a time per connection, so browsers open several connections and queue the rest. HTTP/2 multiplexes many requests over a single connection with compressed headers, which makes pages with lots of files load noticeably faster. HTTP/3 runs over QUIC instead of TCP and copes better with packet loss on mobile networks.
This checker connects to your server, sees which protocol it agrees to through ALPN negotiation, and checks the Alt-Svc header for HTTP/3. Most modern hosts and every major CDN support HTTP/2; if yours does not, it is usually one setting.
Frequently asked questions
Does HTTP/2 need HTTPS?
In practice yes. Browsers only use HTTP/2 over encrypted connections.
Should I still bundle files with HTTP/2?
Less aggressively. HTTP/2 makes many small files cheap, but bundling still helps compression and reduces work for the browser.
How do I enable HTTP/3?
Most easily through a CDN such as Cloudflare, Fastly or Akamai, or on servers like LiteSpeed, Caddy or recent Nginx builds.