HTTP/2, HTTP/3 & Compression Checker

Modern protocols and compression make sites faster. See which ones your server actually offers.

GO DEEPERWhat do you want to uncover next?
⚡ See the negotiated protocol🔒 Check TLS support⚡ Compare response timing

What this tool checks

  • HTTP/2 through TLS ALPN negotiation
  • HTTP/3 advertisement through the Alt-Svc header
  • Brotli and gzip compression
  • Keep-alive
  • HSTS

How to read the result

HTTP/2 is confirmed by a real negotiation. HTTP/3 is reported as advertised when the Alt-Svc header lists it; we do not open a QUIC connection, so it shows advertisement rather than a tested connection.

Terms explained

NginxHTTP Keep-Alive Timeout0-RTTALPNHTTP Request SmugglingOCSP Stapling

Frequently asked questions

Does HTTP/3 matter?

It can help on unreliable mobile networks. Most sites get the larger gain from HTTP/2 plus compression and caching.

Why is Brotli not detected?

The server may only offer gzip, or compress only certain content types. Check your server or CDN settings.

How do I enable HTTP/2?

Enable it on your web server or CDN with a valid HTTPS certificate. Most hosts and CDNs have a one-click option.