1. Source
Live QUIC handshake + Alt-Svc. The result identifies where its evidence came from.
Test whether your web server supports HTTP/3 over QUIC with a live handshake probe. Verify Alt-Svc headers and next-gen protocol performance.
Soumettez une URL publique, un domaine ou un mot-clé. Novaverb ne montrera que les preuves que cet outil peut réellement récupérer ou mesurer.
This check proves whether a real HTTP/3 request over QUIC succeeds, not merely whether HTTP/3 is advertised. Support is reported only when an actual h3 response comes back, so an Alt-Svc header pointing at an endpoint that never answers is reported as advertised and unconfirmed rather than as support.
Live QUIC handshake + Alt-Svc. The result identifies where its evidence came from.
This attempts a real QUIC connection offering ALPN h3 and also reads the Alt-Svc discovery signal. Confirmed means a live HTTP/3 handshake completed; advertised means h3 was announced but not confirmed here.
Utilisez la découverte pour vérifier un problème, puis connectez un espace de travail lorsque vous avez besoin d'historique, de surveillance ou d'analyse à l'échelle du site.
HTTP/3 transporte HTTP sur QUIC, un transport basé sur UDP. Ce vérificateur lit d'abord le signal de découverte HTTPS en direct, puis tente une véritable poignée de main QUIC et une requête HTTP/3. Le résultat sépare une capacité annoncée d'une confirmée.
Vérifiez la connectivité UDP, la politique de CDN, la configuration du certificat/SNI et si la sonde est bloquée. Un en-tête Alt-Svc seul ne prouve pas que QUIC peut se compléter.
Une véritable poignée de main QUIC + HTTP/3 lorsqu'elle est confirmée, ou un signal de découverte clairement étiqueté lorsque seul h3 est annoncé.
Il ne mesure pas la vitesse de la page, les Core Web Vitals, chaque avantage géographique, ou l'utilisation de HTTP/3 par tous les visiteurs.
"Confirmé" signifie qu'une poignée HTTP/3 (QUIC) en direct a été complétée ; "Annoncé" signifie que h3 a été annoncé via Alt-Svc mais non confirmé par cette vérification.
Submit the domain or any URL on the site; only the origin is used. A private host is refused. Bear in mind that HTTP/3 travels over UDP, so a network that blocks QUIC will make a site that genuinely supports it look unsupported from that vantage point, which is a property of the path rather than of the server.
yourdomain.comToute forme d'adresse fonctionne. http ou https, avec ou sans www, un domaine nu ou un chemin complet - nous le normalisons pour vous.https://www.yourdomain.comHTTP/3 fonctionne sur QUIC via UDP 443 ; nous résolvons l'origine et essayons directement.Reading 'unsupported' as a tool errorSi UDP 443 est filtré sur le chemin, une vraie requête h3 ne peut pas se terminer - 'non pris en charge' est alors le bon constat, pas un bug.The Alt-Svc header is read first, because that is how an h3 endpoint is discovered. A real HTTP/3 request is then attempted over QUIC against that endpoint, and the result is reported as supported only when an actual h3 response is received. Advertisement and confirmation are kept as separate findings throughout.
Three IETF specifications define this result. RFC 9114 defines HTTP/3, RFC 9000 defines the QUIC transport it runs on, and RFC 7838 defines the Alt-Svc header used for discovery. Separating discovery from confirmation follows directly from RFC 7838, which describes an advertisement rather than a guarantee.
Complète une vraie requête HTTP/3 pour confirmer le support, pas juste une annonce.
Lisez la spécificationOuvre une connexion QUIC via UDP comme transport pour HTTP/3.
Lisez la spécificationLit l'en-tête Alt-Svc qui annonce un point de terminaison h3 pour la découverte.
Lisez la spécificationIt attempts a real QUIC connection offering ALPN h3 to confirm your server actually speaks HTTP/3, and separately reads the Alt-Svc header to report whether an h3 endpoint is merely advertised.
HTTP/3 is the latest HTTP version, defined in RFC 9114, running over QUIC instead of TCP. QUIC uses UDP, integrates TLS 1.3, and eliminates TCP head-of-line blocking, improving performance on lossy or high-latency networks.
Confirmed means a live HTTP/3 handshake over QUIC actually completed in this test. Advertised means your server announced an h3 option in the Alt-Svc header, but this test did not verify that endpoint responds.
QUIC is a transport protocol over UDP that combines connection setup with TLS 1.3 encryption and supports stream multiplexing without head-of-line blocking. HTTP/3 is HTTP mapped onto QUIC, so confirming HTTP/3 means completing a QUIC handshake.
A server sends an Alt-Svc response header advertising an h3 endpoint, telling clients they may retry over QUIC. Browsers typically connect first over HTTP/2, read Alt-Svc, then upgrade to HTTP/3 on subsequent requests.
Enable QUIC and HTTP/3 in your web server or CDN, allow inbound UDP on port 443 through firewalls, and emit an Alt-Svc header advertising h3. Many sites get HTTP/3 simply by enabling it at their CDN edge.
Often UDP 443 is blocked by a firewall, the QUIC listener is misconfigured, or only the edge speaks h3 intermittently. Advertising via Alt-Svc is a promise; a failed QUIC handshake means clients quietly fall back to HTTP/2.
Not strictly. HTTP/3 mainly helps users on unreliable or high-latency mobile networks by surviving packet loss and network changes better than TCP. It is a worthwhile enhancement rather than a replacement for a working HTTP/2 setup.
Yes. QUIC integrates TLS 1.3 directly into the transport, so HTTP/3 is always encrypted by design. There is no cleartext HTTP/3, and a valid certificate is required for the handshake this test performs.
Only indirectly. Faster, more resilient connections can improve real-user load times and Core Web Vitals, which support rankings. HTTP/3 itself is not a direct ranking factor, and confirming it mainly future-proofs your delivery on modern networks.