Simple C# code showing how you use Custom Attributes from B2C in a solution.

b2c-custom-demo.cs

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

public void Demo(string userObjectId)
{
	/* Lookup the specified user object using object ID
	   GraphClient can be found at https://github.com/AzureADQuickStarts/B2C-GraphAPI-DotNet */
	
	var graphResponse = await GraphClient.GetUserByObjectId(userObjectId);
	var userJson = JObject.Parse(graphResponse);
	
	// this is where our b2c-extension-app App ID is used (minus the dashes)
	var userTierRating = userJson.SelectToken("extension_bb10b272026746f08b6f4367e8b1b1e6_TierRating");
	
}