Definition
HTTP/2, standardized in 2015, introduced request multiplexing, header compression (HPACK), and server push, enabling pages to load much faster than with HTTP/1.1. HTTP/3, based on Google's QUIC protocol, goes further by using UDP instead of TCP, eliminating head-of-line blocking and drastically reducing connection latency. For SEO, these protocols improve Core Web Vitals (LCP, FID, CLS) by speeding up resource loading. Google favors fast sites in its rankings, and adopting HTTP/2 or HTTP/3 can make a measurable difference in load time, especially for resource-heavy sites.
Key Points
- HTTP/2 enables multiplexing multiple requests over a single TCP connection
- HTTP/3 uses QUIC (UDP-based) to eliminate head-of-line blocking
- Adopting these protocols directly improves Core Web Vitals
Practical Examples
Migration to HTTP/2
An e-commerce site migrates from HTTP/1.1 to HTTP/2 and sees a 30% reduction in load time thanks to multiplexing, improving its LCP and rankings.
HTTP/3 with QUIC
An international media site enables HTTP/3 via Cloudflare and observes significant performance improvement for mobile users on unstable networks.
Frequently Asked Questions
HTTP/3 offers additional latency gains thanks to QUIC, especially for unstable mobile connections. However, HTTP/2 already represents a major improvement over HTTP/1.1. The SEO impact depends on your audience and infrastructure.
Use Chrome DevTools (Network tab, Protocol column), or online tools like KeyCDN HTTP/2 Test. For HTTP/3, check for the alt-svc header in server responses.
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Last updated: 2026-02-07