Create a websocket server in .net core console application

Self-hosted ASP.net Core applications are in fact console applications, using Kestrel as the server you can run it in non-blocking and continue the program as a regular console one, something like this:

public static void Main(string[] args)
{

    var host = new WebHostBuilder()
        .UseKestrel()
        .Build();                     //Modify the building per your needs

    host.Start();                     //Start server non-blocking

    //Regular console code
    while (true)
    {
        Console.WriteLine(Console.ReadLine());
    }
}

The only downside of this is you will get some debug messages at the begining, but you can supress those with this modification:

public static void Main(string[] args)
{

    ConsOut = Console.Out;  //Save the reference to the old out value (The terminal)
    Console.SetOut(new StreamWriter(Stream.Null)); //Remove console output

    var host = new WebHostBuilder()
        .UseKestrel()
        .Build();                     //Modify the building per your needs

    host.Start();                     //Start server non-blocking

    Console.SetOut(ConsOut);          //Restore output

    //Regular console code
    while (true)
    {
        Console.WriteLine(Console.ReadLine());
    }
}

Source about the console output.