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Version: 1.0

HTTP/3 and QUIC

HTTP/3 is the third major revision of the HTTP protocol. Instead of TCP, it's built on QUIC, a UDP-based transport that was designed with multiplexed HTTP in mind. This gives HTTP/3 several advantages over HTTP/1.x:

  • Faster connection setup — QUIC combines the transport and TLS handshakes, reducing round trips from three (TCP + TLS 1.3) to one.
  • No head-of-line blocking — HTTP/3 sends each request on an independent QUIC stream. A stalled or slow response doesn't delay any other response on the same connection.
  • Better performance on lossy networks — particularly relevant for mobile clients where packet loss is common.

Adding HTTP/3 to a server​

The trillium-quinn crate adds HTTP/3 support to any Trillium server. It runs a QUIC endpoint alongside the existing TCP listener. Protocol selection happens automatically: browsers use ALPN during the TLS handshake to negotiate HTTP/3, and the server advertises support via Alt-Svc headers so clients know to use QUIC on future connections.

use trillium::Conn;
use trillium_quinn::QuicConfig;
use trillium_rustls::RustlsAcceptor;

fn main() {

    trillium_tokio::config()
        .with_acceptor(RustlsAcceptor::from_single_cert(cert, key))
        .with_quic(QuicConfig::from_single_cert(cert, key))
        .run(|conn: Conn| async move { conn.ok("hello!") });
}

As with HTTP/2, the same handler receives Conn objects regardless of whether they arrived over HTTP/1.x, HTTP/2, or HTTP/3. No changes to application logic are required.

ℹ️ TLS is required for HTTP/3. The RustlsAcceptor and QuicConfig can be initialized from the same certificate and key files.

Crypto providers​

trillium-quinn uses aws-lc-rs as its crypto backend by default. To use ring instead, enable the ring feature and disable aws-lc-rs.

HTTP/3 client​

The trillium-client HTTP client can upgrade to HTTP/3 automatically when a server advertises support via Alt-Svc. See the HTTP Client page for details.

WebTransport​

WebTransport is a browser API built on top of HTTP/3 that provides multiplexed streams and datagrams for real-time communication. It requires HTTP/3 to be configured. See WebTransport for details.