HTTP/2, HTTP/3 and IPv6 support

Does the site support the modern, faster protocols?

Live lookupPlain English + technicalFree, no sign-upBeta

Good to know: Checks HTTP/2 and HTTP/3 support and whether the site publishes IPv6 (AAAA) records.

How to read the results

Green ticks are supported. HTTP/3 is advertised via Alt-Svc or an HTTPS DNS record.

Check everything at once

The health check runs this and 30 more checks on a domain, then ranks what to fix.

Guides for auditors

Compliance checks

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About the HTTP/2, HTTP/3, IPv6 support

Check whether a website supports HTTP/2, HTTP/3 (QUIC) and IPv6, using ALPN, Alt-Svc, HTTPS DNS records and AAAA records.

Every result comes in two styles: plain English for everyone, and the exact technical detail for engineers, with the raw JSON one click away.

Questions

It helps on mobile and lossy networks. Most CDNs turn it on with one switch.