Why it matters
Google's crawlers support HTTP/1.1, their default, and HTTP/2, and use whichever crawls best; Googlebot does not support HTTP/3 today. HTTP/2 can save server resources but gives no ranking benefit, and a site can opt out of HTTP/2 crawling by answering such requests with 421.
How to meet it
Make every crawlable host answer over HTTP/1.1. HTTP/2 may save server resources and is worth enabling on the origin and the CDN; to opt out of HTTP/2 crawling, return 421 to Google's HTTP/2 requests. Treat HTTP/3 as an extra for browsers. Check that CDN, firewall and load-balancer rules written for HTTP/3 (QUIC) traffic do not break HTTP/1.1 or HTTP/2 responses. Support gzip or Brotli compression, which Google's crawlers accept.
How to test it
curl -I --http1.1 https://www.example.com/ returns 200, and curl -I --http2 https://www.example.com/ returns the same status, canonical, robots and caching headers (Date and similar headers may differ), unless the site deliberately answers 421 to opt out of HTTP/2 crawling; Crawl stats shows normal response times.
How Regensbot covers it
Decided from one URL.
An audit reads the response, the headers, the HTML, robots.txt, the sitemaps and the structured data, and the finding shows the evidence it saw.
Sources
Google documents01
Claims in the knowledge base04
- D1-C076SourceDay 1, session not recordedGoogle's documentation
- D1-C075ConsistentDay 1, session not recordedSaid on stage
- D1-C077n/aDay 1, session not recordedThe author's interpretation
- D1-C139SourceDay 1, session not recordedGoogle's documentation
Claim IDs refer to the Search Central Live 2026 knowledge base. The knowledge base (opens in a new tab)
- Consistent
- Google's documentation supports it without stating it.
- Source
- The claim is the cited document itself.
- n/a
- Nothing to verify: a quotation, framing, opinion or analysis.