What Are Some Options To Convert Url-Encoded Form Data to JSON in .Net

I have a web request that is sending the server data that is in the format application/x-www-form-urlencoded. I would like to convert it to application/json.

Example:

URL-encoded form data:

Property1=A&Property2=B&Property3%5B0%5D%5BSubProperty1%5D=a&Property3%5B0%5D%5BSubProperty2%5D=b&Property3%5B1%5D%5BSubProperty1%5D=c&Property3%5B1%5D%5BSubProperty2%5D=d

Pretty version:

Property1=A
Property2=B
Property3[0][SubProperty1]=a
Property3[0][SubProperty2]=b
Property3[1][SubProperty1]=c
Property3[1][SubProperty2]=d

The above data needs to be converted to the following JSON data:

{
    Property1: "A",
    Property2: "B",
    Property3: [
        { SubProperty1: "a", SubProperty2: "b" },
        { SubProperty1: "c", SubProperty2: "d" }]
}

Question:

Are there any free tools that are capable of doing this? I have not been able to find any myself and if they exist, I'd rather consume them than writing one myself, but if it comes to that, I will.

A C#/.Net solution is preferred.