About Data Conversation in Json

Hii Experts

i want to convert my data in json string and pass it at client side.

for that i am using javascriptseralizer and convert my data in json string as below

JavaScriptSerializer js = new JavaScriptSerializer();

string jsondata = js.Serialize(customer);

In mvc we can do it directly as below

string jsondata=Json(customer);

I want that same in simple c# web forms but i dont know which librery is included in mvc for Json();

any one help please how can ido it ??