.NET 10 new WebSocketStream API

Program.cs

using System.Net.WebSockets;
using System.IO;

// Client side, streaming supported over WebSockets
var client = new ClientWebSocket();
await client.ConnectAsync(new Uri("wss://example.com/upload"), CancellationToken.None);

using var wsStream = WebSocketStream.Create(client);
await using var fileStream = File.OpenRead("bigfile.zip");

// Copy file to WebSocket stream
await fileStream.CopyToAsync(wsStream);