1.  Install Microsoft's IIS CORS module from https://www.iis.net/downloads/microsoft/iis-cors-module.
2. Find the web.config file of the IIS website on which your FotoWeb site is hosted.

DO NOT modify the web.config file in the Documents folder of the FotoWeb site! Your changes will be overwritten with every update. Instead, the web.config file of the website is free for you to customize. You can find its location by right-clicking on the website in IIS Manager and selecting Explore. For example, for Default Web Site, the location of the configuration file is typically C:\inetpub\wwwroot\web.config. If you create additional web sites, then each will have its own configuration file in a separate location that you choose, and you can and need to configure CORS separately for each site.

3.  Add the following XML block under the <system.webServer> XML tag:

<cors enabled="true">
 <add origin="https://your-application.net" maxAge="120">
 <allowMethods>
 <add method="*"/>
 </allowMethods>
 <allowHeaders>
 <add header="*"/>
 </allowHeaders>
 </add>
</cors>

 This enables CORS from the given domain (in this case, https://your-application.net).

For more detailed configuration options, see the IIS CORS module official documentation (external link). Not all configurations will work with the FotoWeb API; only configurations documented here have been tested. If you think your configuration should work but doesn't, and it is required (due to a security policy required by your IT team, for example), contact Fotoware for support.