What is the difference between HTTP/2 and HTTP/3?

Both protocols speed up transfer compared to the old HTTP/1.1, but they solve different problems. HTTP/2 introduced multiplexing, meaning several parallel requests over a single connection instead of opening a new one for every file. This removes much of the former connection overhead. One weakness remains, however: if a packet is lost, the entire TCP connection stalls (head-of-line blocking).

HTTP/3 relies on the QUIC protocol over UDP and solves exactly this, because a lost packet only blocks the affected stream, not all of them. Connection setup is also faster. The biggest gain is felt by users on unstable mobile connections. As part of server optimization, we configure your server to offer both protocols, so every visitor automatically uses the fastest available variant.