how to gzip content in asp.net MVC?

For .NET Core 2.1 there is a new package that can be used ( Microsoft.AspNetCore.ResponseCompression )

Simple sample to get going, after installing the package:

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddResponseCompression();

        services.AddResponseCompression(options =>
        {
            options.Providers.Add<GzipCompressionProvider>();
            options.EnableForHttps = true;
        });
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseResponseCompression();
    }
}

You can read more about it here: https://docs.microsoft.com/en-us/aspnet/core/performance/response-compression?view=aspnetcore-2.1&tabs=aspnetcore2x