How to parse Json value of arrays c#

Although the JSON response you are getting is valid JSON as a whole, it isn't in a form that would allow you to extract the dates and decimals easily with a standard JSON library.

The first problem is that the "array" part is actually inside a string value. You might think that you could simply take the string value and try to re-parse it as JSON, but then you will hit another problem: the string value by itself is not valid JSON array, as @Blender noticed. In order for it to be valid, the date values would need to be quoted, since JSON does not have a native date representation.

So, one way or another, you will have to do some manual processing on the data to extract the values. Fortunately, this is not very difficult using regular expressions to split up the string. Here's the approach I would take:

First, define a simple class to hold your data items.

class DataItem
{
    public DateTime Date { get; set; }
    public double Number { get; set; }
}

Then, picking up where you left off, you can parse apart your data string like this:

List<DataItem> timeSeriesData = new List<DataItem>();
string[] pairs = Regex.Split(data, @"\[\[|\],\[|\]\]");
foreach (string pair in pairs)
{
    if (!string.IsNullOrEmpty(pair) && char.IsDigit(pair[0]))   // sanity check
    {
        string[] parts = pair.Split(',');
        DateTime date = DateTime.Parse(parts[0], CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind);
        double number = double.Parse(parts[1]);
        timeSeriesData.Add(new DataItem { Date = date, Number = number });
    }
}

Now you can use the timeSeriesData list as you see fit.