C# HttpClient with an authenticated residential proxy (.NET 6+, WebProxy + NetworkCredential) — https://quantumproxies.io/residential-proxies

CSharpProxyExample.cs

// C# HttpClient behind an authenticated residential proxy (.NET 6+).
//
// Notes that save you an afternoon:
// - WebProxy + NetworkCredential handles the 407 dance automatically.
// - Reuse ONE HttpClient; a new handler per request leaks sockets.
// - Geo flags live in the proxy username (-country-de, -session-x1-lifetime-10).
//
// Proxy: QuantumProxies residential — https://quantumproxies.io/residential-proxies
// Credentials: https://app.quantumproxies.io/register

using System.Net;

var user = (Environment.GetEnvironmentVariable("QP_USER") ?? "YOUR_USERNAME") + "-country-us";
var pass = Environment.GetEnvironmentVariable("QP_PASS") ?? "YOUR_PASSWORD";

var handler = new HttpClientHandler
{
    Proxy = new WebProxy("http://residentialboson.quantumproxies.io:9000")
    {
        Credentials = new NetworkCredential(user, pass)
    },
    UseProxy = true,
};

using var client = new HttpClient(handler);
var json = await client.GetStringAsync("https://ipinfo.io/json");
Console.WriteLine(json);

// Sticky session variant (same exit IP for 10 minutes — port 10000):
//   new WebProxy("http://residentialboson.quantumproxies.io:10000")
//   user = $"{baseUser}-country-us-session-cs1-lifetime-10"