HTTP/3 & QUIC: 2026 Adoption Report
Enterno.io scanned the top-1M sites via ALPN negotiation: 34% support HTTP/3 (up +8% year-over-year). Leaders — Cloudflare (98% HTTP/3), Google (96%), Fastly (91%). Adoption on origin servers without a CDN is only 2.3%. First-connection mobile gain vs HTTP/2 over TLS 1.3 is ~180ms TTFB.
Below: key findings, platform breakdown, implications, methodology, FAQ.
Key Findings
| Metric | Pass-rate / Value | Median | p75 |
|---|---|---|---|
| HTTP/3 enabled (top-1M) | 34.1% | — | — |
| HTTP/3 via Cloudflare | 98% | — | — |
| HTTP/3 via Fastly | 91% | — | — |
| HTTP/3 at origin (no CDN) | 2.3% | — | — |
| HTTP/2 only | 58% | — | — |
| HTTP/1.1 only (legacy) | 7.9% | — | — |
Breakdown by Platform
| Platform | Share | Pass / Detail | avg LCP |
|---|---|---|---|
| Cloudflare | 21% | HTTP/3: 98% | — |
| AWS CloudFront | 14% | HTTP/3: 76% | — |
| Fastly | 4% | HTTP/3: 91% | — |
| Google Cloud CDN | 5% | HTTP/3: 96% | — |
| Azure Front Door | 3% | HTTP/3: 68% | — |
| Origin (no CDN) | 46% | HTTP/3: 2% | — |
Why It Matters
- HTTP/3 over QUIC (UDP) removes head-of-line blocking — on lossy mobile networks LCP improves by up to 300ms
- Cloudflare enables HTTP/3 by default — 21% of all sites got HTTP/3 for free
- nginx HTTP/3 was experimental until 1.25, stable since March 2023 — origin-server adoption will grow
- Yandex Browser and Chrome support HTTP/3 since 2020, Safari since 2023 — 95%+ client coverage
Methodology
Scan of the top-1M per Tranco list (March 2026). Used curl --http3 and nghttp3 to verify ALPN negotiation for HTTPS ports. CDN identified by SOA/CNAME chain and Server header. TTFB measured from three geographies (Frankfurt, Virginia, Singapore) × 5 repeats per URL.
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How-to
Frequently Asked Questions
Why aren't origin servers moving to HTTP/3?
Three reasons: (1) nginx HTTP/3 stable only since 1.25 (March 2023); (2) kernel UDP performance on Linux trails TCP in non-CDN scenarios; (3) operational complexity of QUIC (retries, NAT rebinding).
Is HTTP/3 always faster?
On fast wired connections it is a close call (HTTP/2 TCP + BBR is comparable). The gain shows up on mobile/Wi-Fi with packet loss — typically 100-200ms TTFB.
Do I need to change application code?
No. HTTP/3 is a transport-level change; the API is identical to HTTP/2. Only proxy/edge server configuration changes.
How do I check if a site uses HTTP/3?
<a href="/en/ssl">Enterno SSL/TLS Checker</a> shows supported protocols including HTTP/3. Or at the terminal: <code>curl -I --http3 https://example.com</code>.