How to add gzip compression to ASP.NET Core API responses

If you're using ASP.NET Core 2.x, you need to install the NuGet Microsoft.AspNetCore.ResponseCompression

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<GzipCompressionProviderOptions>(options => 
    {
        options.Level = CompressionLevel.Fastest;
    });
    services.AddResponseCompression(options =>
    {
        options.Providers.Add<GzipCompressionProvider>();
    });
}

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

Source: Response compression in ASP.NET Core