How to use CORS in ASP.NET Core minimal APIs

"In the "Additional Information" window shown next, select ".NET 9.0 (Standard Term Support)" as the framework version and uncheck the check box that says "Use controllers," as we'll be using minimal APIs in this project. Elsewhere in the "Additional Information" window, leave the "Authentication Type" set to "None" (the default) and make sure the check boxes "Enable Open API Support," "Configure for HTTPS," and "Enable Docker" remain unchecked. We won't be using any of those features here."

"An origin of an HTTP request comprises a scheme, a host, and a port number. Any two HTTP requests are from the same origin if they have the same scheme, host, and port number. If any of these differ, then the HTTP requests are cross-origin, i.e., they do not belong to the same origin. Web browsers have used the same-origin policy for many years. The same-origin policy disallows web pages or scripts loaded from one origin from making HTTP requests to a different origin."

Launch Visual Studio 2022 and create a new ASP.NET Core Web API project. Select the ASP.NET Core Web API template, configure project name and location, and (optionally) place solution and project in the same directory. In Additional Information choose .NET 9.0 (Standard Term Support) and uncheck Use controllers to use minimal APIs. Leave Authentication Type as None and keep Enable Open API Support, Configure for HTTPS, and Enable Docker unchecked. An HTTP request origin comprises scheme, host, and port. Requests with identical scheme, host, and port are same-origin; differing values produce cross-origin requests. Browsers enforce the same-origin policy to block cross-origin requests for security.

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