HTTP/2 and HTTP/3 support: Crawl Audit check 94

Short answer: HTTP/2 and HTTP/3 are newer versions of the protocol browsers use to fetch your pages. They can fetch many files over one connection at once, where HTTP/1.1 queues them. Check 94 passes when your server agrees to HTTP/2 or HTTP/3. Most modern hosts and CDNs offer them by default.

What Crawl Audit checks

• When Crawl Audit opens a secure connection to your site, it records the protocol the server agrees to use (through a step called ALPN).
• Pass: h2 (HTTP/2) or h3 (HTTP/3). Warning: only HTTP/1.1.
• If the protocol can't be read, Crawl Audit passes sites whose headers show Cloudflare, Vercel, Fastly or Akamai, which support HTTP/2, and warns otherwise.

What the sources say

• MDN: the goals of HTTP/2 are "to reduce latency and head-of-line blocking, by enabling full request and response multiplexing and support for request prioritization".
• MDN: "The most notable difference in HTTP/3 is that it uses a protocol named QUIC over UDP instead of TCP." It "reduces latency and eliminates the head-of-line blocking problem in HTTP."

Both work only over HTTPS in browsers, so an HTTPS certificate comes first (check 48).

On your platform

• Cloudflare: "HTTP/2 is enabled by default for all plans". "HTTP/3 is available to all plans", switched on under Speed, Settings, Protocol Optimization.
• Vercel: its CDN negotiates HTTP/1.1 and HTTP/2.
• Shopify: "All assets are served using HTTP/2".
• Your own server: recent nginx and Apache versions support HTTP/2 with a configuration change.

Sources

• MDN, HTTP/2 and HTTP/3, checked 3 October 2026.
• Cloudflare, HTTP/2 and HTTP/3; Vercel, CDN security; Shopify, Improving web performance.