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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.

    iisexpress-proxy defaults to http, so if your application is running https, then include the full URL.

    iisexpress-proxy https://localhost:51123 to 3000

    Note that this will terminate HTTPS. On your destination machine, connect to port 3000 using HTTP, not HTTPS.

    If you want the proxy itself to server HTTPS, you can specify the target with the full URL as well.

    iisexpress-proxy https://localhost:51123 to https://*:3000

    This will generate a self-signed certificate and use it, openssl must be in PATH for this to work.

    If you want to bind to a specific interface instead of all of them, use its IP in the target URL, e.g.

    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 proxyHost: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

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

    For another advanced example, consider that you're on public Wifi and don't want to publicly expose your dev server. You could set up a VPN between your laptop and your phone and only expose the server on the VPN interface ( Then you can run

    iisexpress-proxy 5000 to

    ...and open on your phone with VPN enabled, while other wifi users won't be able to connect.

    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

    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.


    npm i iisexpress-proxy

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    • icflorescu