A simple local proxy useful for accessing IIS Express from remote machines.

Usage no npm install needed!

<script type="module">
  import alancnetIisexpressProxy from 'https://cdn.skypack.dev/@alancnet/iisexpress-proxy';



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A simple, yet practical command-line utility enabling .NET developers to test web applications served by IIS Express on remote devices.


Are you a .NET developer building mobile web applications? Have you ever been frustrated by the fact that there's no easy way to enable IIS Express to accept connections from remote devices?...


There's no need to install iisexpress-proxy if you're using npm@^5.2.0; you can simply run it with npx. If you're using an older version of npm, you'll most likely want iisexpress-proxy installed as a global module:

npm install -g iisexpress-proxy

Note: You need to have Node.js installed.


If you're using npm@^5.2.0:

npx iisexpress-proxy localPort to proxyPort

Alternatively, if you installed iisexpress-proxy as a global npm module:

iisexpress-proxy localPort to proxyPort

For instance, if your application's IIS Express port is 51123, run this in the Command Prompt:

iisexpress-proxy 51123 to 3000

The program will list the external addresses you can use for testing your application on remote devices.

Advanced usage (VPN, virtual hosts, etc.)

You can also use iisexpress-proxy to expose an IIS server instance running on a different host accessible through VPN, like this:

iisexpress-proxy host:port to proxyPort

For instance, let's conside this scenario:

  • the application is running on and it only accepts connections from clients within a VPN;
  • your development machine has a network interface within the same VPN and another publicly accessible one (;
  • you need to test the application from mobile devices without having to add those devices to the VPN.

By running this in the Command Prompt:

iisexpress-proxy to 3000

...you'll be able to access the application by pointing the mobile devices to

Note: This functionality was added at v1.1.0 (released 10/21/2015).

WebSocket support was added in v1.4.0 by Stan Hebben - see PR #11 for details.


iisexpress-proxy doesn't work in scenarios involving integrated Windows authentication (see issue #here).

How does it work

It's proxying the HTTP traffic on localPort to proxyPort on all the available network interfaces and it's also changing the origin of the host header, allowing you to test web applications hosted by IIS Express on various remote devices (mobile devices, other desktops, etc.).

If you need to access the original host requested by the browser, the request headers will include X-Forward headers. In ASP.NET, Request.Headers["x-forwarded-host"] will contain the requested host.

Credits and attributions

This command-line utility wraps http-proxy. The original http-proxy logo was created by Diego Pasquali.

Endorsing the author

If you find this repo useful, please give it a star, tweet about it and endorse me on LinkedIn:

Ionut-Cristian Florescu on LinkedIn

Looking for co-maintainers

I've completely switched away from .NET / IIS / Windows, so I'm not using iisexpress-proxy in my work anymore. I'm almost exclusively using Linux and macOS now, which means there's little incentive for me to actively contribute to this project anymore. I'll keep maintaining it and will gladly accept PRs, of course, but having a co-maintainer constantly using Windows as a development machine would be beneficial for the community. Please let me know if you're interested.

Before raising issues

I'm getting lots of questions from people just learning to do web development or simply looking to solve a very specific problem they're dealing with. While I will answer some of them for the benefit of the community, please understand that open-source is a shared effort and it's definitely not about piggybacking on other people's work. On places like GitHub, that means raising issues is encouraged, but coming up with useful PRs is a lot better. If I'm willing to share some of my code for free, I'm doing it for a number of reasons: my own intellectual challenges, pride, arrogance, stubbornness to believe I'm bringing a contribution to common progress and freedom, etc. Your particular well-being is probably not one of those reasons. I'm not in the business of providing free consultancy, so if you need my help to solve your specific problem, there's a fee for that.


The ISC License.