Understanding CORS

CORS is essentially the ability to request a resource from one domain from a page being served by a different domain: think, for example, of a page at http://mysite.com requesting a JavaScript file from http://javascriptdepository.com. This is done in all big portals—for example, for including visitor tracking or ad scripts. Modern browsers forbid this by default, but it is possible to enable it on a case-by-case basis.

If you want to learn more about CORS, please consult https://developer.mozilla.org/en/docs/Web/HTTP/Access_control_CORS.

ASP.NET Core supports CORS servicing. You first need to register the required services (in ConfigureServices), like this:

services.AddCors();

Or, a slightly more complex example involves defining a policy, like this:

services.AddCors(options =>
{
    options.AddPolicy("CorsPolicy", builder =>
        builder
            .AllowAnyOrigin()
            .AllowAnyMethod(...