If camelCase property names are not being used in the JSON responses of your ASP.NET Core 6 Web API, it's likely because the default JSON serialization settings are set to use PascalCase by default. To make your API use camelCase property names, you can configure the JSON serialization settings as follows:

1. In your Startup.cs file, within the ConfigureServices method, configure the JSON serializer to use camelCase:

services.AddControllers()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.PropertyNamingPolicy = null; // Use the default naming policy
    });

1. Alternatively, you can set options.JsonSerializerOptions.PropertyNamingPolicy to JsonNamingPolicy.CamelCase to explicitly specify camelCase:

services.AddControllers()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase; // Use camelCase naming policy
    });

Either of the above methods will configure the JSON serialization settings to use camelCase for property names. Your API will now return JSON responses with camelCase property names. Make sure you have added the necessary Microsoft.AspNetCore.Mvc.NewtonsoftJson NuGet package and added it to your project if you prefer using Newtonsoft.Json for serialization.