HTTP/3 in .NET 6

.NET 6 adds HTTP/3 support to Kestrel. HTTP/3 uses **QUIC** (UDP-based), avoiding head-of-line blocking that plagues TCP-based HTTP/2.

Enabling HTTP/3

builder.WebHost.ConfigureKestrel(options =>
{
    options.ListenAnyIP(5001, listenOptions =>
    {
        listenOptions.Protocols = HttpProtocols.Http1AndHttp2AndHttp3;
        listenOptions.UseHttps();
    });
});

Client Usage

var client = new HttpClient { DefaultRequestVersion = HttpVersion.Version30 };
var response = await client.GetAsync("https://localhost:5001");

Key Takeaways

• Browsers negotiate HTTP/3 automatically via Alt-Svc header.
• Ideal for high-latency networks (mobile).
• Requires TLS 1.3.