Let's face it... debugging ASP.NET production websites can be challenging. HTML sessions are 'stateless', meaning from one post to the next, the server has no idea what post came first. For example, let's say there is a website that prompts the user for their name on one page, and on the subsequent page the user is prompted for their address. Well, the server has no intrinsic way to join the data together from those two pages to save it all in a table somewhere.
Well, this ViewState is stored right in the web page as a 64 bit encoded string. It's not encoded but definitely looks that way. It's unreadable without a decoder. Anyway... If something is stored in the ViewState, programmers can have a bitch of a time trying to pull it apart and see the data. But... This information can be invaluable to debugging a production problem. There are varied ViewState tools on the web for decoding this gobeldygook into something that is somewhat coherent. I use Base64 decoder and encoder at motobit. It's simple and works.