Enabling CORS in IISExpress

I was playing around with swagger-ui and was trying to point it to a local endpoint that I started with IIS Express. I was getting an error saying that it needed the endpoint to accept Access-Control-Allow-Origin requests.

I went Googling and it couldn’t find anything specific to IIS Express but managed to use some guidance for full blown IIS.

The solution is to go to C:\Program Files (x86)\IIS Express\AppServer and open the applicationhost.config file.

Search for httpProtocol and you should see this:

<httpProtocol>
    <customHeaders>
        <clear />
        <add name="X-Powered-By" value="ASP.NET" />
    </customHeaders>
    <redirectHeaders>
        <clear />
    </redirectHeaders>
</httpProtocol>

Now add this to the customHeaders node:

<add name="Access-Control-Allow-Origin" value="*" />
<add name="Access-Control-Allow-Headers" value="Content-Type" />

Just bear in mind this opens up your webserver so you may need to find something alternative for a live production environment.

Anyway you should now be able to start accepting requests via CORS when you fire up IISExpress