Is it possible to have NSwag ignore a controller?

Use [OpenApiIgnore]

(since [SwaggerIgnore] has been deprecated)

I think in the latest version,

[ApiExplorerSettings(IgnoreApi = true)]

is supported.

Otherwise you can add the SwaggerIgnoreAttribute OR OpenApiIgnoreAttribute attribute

[SwaggerIgnore]
[OpenApiIgnore]

Or manually select the controllers in NSwagStudio or in the middleware...