How can I parse some JSON dynamically without knowing JSON values?

This is official documentation of Newtonsoft method you are trying to use.

https://www.newtonsoft.com/json/help/html/Overload_Newtonsoft_Json_JsonConvert_DeserializeObject.htm

If an API's method returns different json propeties and you cannot trust it's property names all the times, then you can try using a deserialize method that returns .Net object, for example: JsonConvert.DeserializeObject Method (String) https://www.newtonsoft.com/json/help/html/M_Newtonsoft_Json_JsonConvert_DeserializeObject.htm

That method's signature is this: public static Object DeserializeObject(string value)

Parameter is: value of type json string.

Return Value is: Object of type object.

If you do not want an Object, then you can of course use a .Net type you have. Such as this method: JsonConvert.DeserializeObject Method (String)

Any property that you have in both (the .net type and json object) will get populated. If .net type has properties that do not exist in json object, then those will be ignored. If json object has properties that do not exist in.net, then those will be ignored too.

Here's an example of a .Net type

using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using Newtonsoft.Json.Serialization;
using System.Collections.Generic;
using System.IO;
using System.Text;

namespace MyNameSpace
{
    public class TDAmeritradeStockData
    {
        [JsonProperty("symbol")]
        public string Symbol { get; set; }
        [JsonProperty("status")]
        public string Status { get; set; }
        [JsonProperty("callExpDateMap")]
        public object CallExpDateMap { get; set; }
        //...
        //...

        public CallExpDateMapType[] CallExpDateMapList { get; set; }
    }

    public class CallExpDateMapType
    {
        [JsonProperty("expirationdate")]
        public string Expirationdate { get; set; }
        [JsonProperty("StrikePrice")]
        public List<StrikePriceType> StrikePriceList { get; set; }
    }

    public class StrikePriceType
    {
        public string StrikePrice { get; set; }
        public List<StrikePricePropertiesType> StrikePricePropertiesList { get; set; }
    }

    public class StrikePricePropertiesType
    {
        [JsonProperty("putCall")]
        public string PutCall { get; set; }
        [JsonProperty("symbol")]
        public string Symbol { get; set; }
        [JsonProperty("description")]
        public string Description { get; set; }
        [JsonProperty("exchangeName")]
        public string ExchangeName { get; set; }
        [JsonProperty("bid")]
        public double Bid { get; set; }
        [JsonProperty("ask")]
        public double Ask { get; set; }
        //...
        //...
    }

    [TestClass]
    public class TestTestTest
    {
        [TestMethod]
        public void JsonTest()
        {
            var jsondata = ReadFile("data.json");

            var model = JsonConvert.DeserializeObject<TDAmeritradeStockData>(jsondata);

            JObject jObject = (JObject)model.CallExpDateMap;

            var count = ((JObject)model.CallExpDateMap).Count;
            model.CallExpDateMapList = new CallExpDateMapType[count];

            var jToken = (JToken)jObject.First;

            for (var i = 0; i < count; i++)
            {
                model.CallExpDateMapList[i] = new CallExpDateMapType
                {
                    Expirationdate = jToken.Path,
                    StrikePriceList = new List<StrikePriceType>()
                };

                var nextStrikePrice = jToken.First.First;

                while (nextStrikePrice != null)
                {
                    var nextStrikePriceProperties = nextStrikePrice;

                    var srikePriceList = new StrikePriceType
                    {
                        StrikePrice = nextStrikePriceProperties.Path,
                        StrikePricePropertiesList = JsonConvert.DeserializeObject<List<StrikePricePropertiesType>>(nextStrikePrice.First.ToString())
                    };

                    model.CallExpDateMapList[i].StrikePriceList.Add(srikePriceList);

                    nextStrikePrice = nextStrikePrice.Next;
                }

                jToken = jToken.Next;

            }

            Assert.IsNotNull(model);
        }

        private string ReadFile(string fileName)
        {
            using (var fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read))
            {
                var data = new StringBuilder();
                using (var streamReader = new StreamReader(fileStream))
                {
                    while (!streamReader.EndOfStream) data.Append(streamReader.ReadLine());
                    streamReader.Close();
                }
                fileStream.Close();
                return data.ToString();
            }
        }
    }  
}