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This project is mostly discontinued. Please look at Kestrel. I will have to resurect this one only in case Kestrel will not be stable and usable soon enough. If you don't agree with this speak yourself up in issues.

Fast and scalable Owin Web Server in pure .Net 4.5 (it does not use HttpListener)

Additional library for Owin Acme client with sample Nowin server updating Certificate completely automatically, which also redirect all http to https.

Current status is usable for testing, not for production, nobody did any security review, you have been warned. On Windows speed is better than NodeJs and in some cases even better than HttpListener.

Features it supports:

  • Http 1.0 and 1.1 clients uses SocketAsyncEventArgs in most optimal way you can found on the Internets
  • KeepAlive, untested pipe-lining, automatic chunked en/decoding of request and response
  • Everything strictly asynchronous and parallel automatically using all available cores
  • SSL using .Net SSL Stream so in theory it should be same secure
  • WebSockets in platform independent way! It buffers data so SignalR is more optimal on wire than current HttpListener on Win8.
  • Tracks currently connection counts and maximum allocated connections and allocates new as needed
  • One connection needs less than 26kb RAM and most of it is reused but never deallocated.
  • By default settings maximum size of request and response headers are 8KB.
  • Published in Nuget for easy use. No dependencies.
  • Live updating of Https certificate
  • Completely working Acme Let's encrypt client middleware. Behind it uses again just pure .Net code, though it needs .Net 4.6. Middleware itself is independent of Nowin, just sample usage shows how to use it together.

Sample: (uses Microsoft.Owin.Hosting nuget)

static class Program
    static void Main(string[] args)
        var options = new StartOptions
            ServerFactory = "Nowin",
            Port = 8080

        using (WebApp.Start<Startup>(options))
            Console.WriteLine("Running a http server on port 8080");

public class Startup
    public void Configuration(IAppBuilder app)
        app.Use(context =>
            if (context.Request.Path == "/")
                context.Response.ContentType = "text/plain";
                return context.Response.WriteAsync("Hello World!");

            context.Response.StatusCode = 404;
            return Task.Delay(0);

Https sample using builder:

var builder = ServerBuilder.New().SetPort(8888).SetOwinApp(SomeOwinApp);
builder.SetCertificate(new X509Certificate2("certificate.pfx", "password"));
using (builder.Start())
    Console.WriteLine("Listening on port 8888. Enter to exit.");

If running on OSX/Linux and MonoDevelop/Xamarin, to use the above sample please select external console in your project options by going to Options / Run / General / Run on external console


Owin Web Server in pure .Net







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