How to decode viewstate

Question

I need to see the contents of the viewstate of an asp.net page. I looked for a viewstate decoder, found Fridz Onion's ViewState Decoder but it asks for the url of a page to get its viewstate. Since my viewstate is formed after a postback and comes as a result of an operation in an update panel, I cannot provide a url. I need to copy & paste the viewstate string and see what's inside. Is there a tool or a website exist that can help viewing the contents of viewstate?

Answer 1

Use Fiddler and grab the view state in the response and paste it into the bottom left text box then decode.

Answer 2

Isn't it just a base 64 encoded version of the serialized data?

Answer 3

Darren's suggestion worked but apparantly decoder did not like my viewstate string. It gives a "the serialized data is invalid" message.

Answer 4

As another person just mentioned, it's a base64 encoded string. In the past, I've used this website to decode it:

http://www.motobit.com/util/base64-decoder-encoder.asp

Answer 5

You can ignore the URL field and simply paste the viewstate into the Viewstate string box.

It does look like you have an old version; the serialisation methods changed in ASP.NET 2.0, so grab the 2.0 version

Answer 6

@blowdart:

I already have that version.

I also tried with the site joshhinman has suggested but what i got was some meaningless chars. May be there is a problem with my viewstate string. Is it possible (since it is auto-generated, i do not think it is broken)?

Answer 7

buyutec, stupid question: are you encrypting your viewstate? If you are, you (obviously) won't be able to decode it. I imagine you probably already thought of this, but it shouldn't go unmentioned.

Answer 8

@joshhinman

(: No, I do not encrypt it.

Answer 9

Normally, ViewState should be decryptable if you have the machine-key, right? After all, ASP.net needs to decrypt it, and that is certainly not a black box.

Answer 10

What happens if ASP.NET cannot read it?

I have a repeater on the page which loses its data. When the page posts back, i cannot see its items through Items property. That's why I am trying to read the viewstate and check for a problem. May a broken viewstate be the reason?

Answer 11

@Michael

of course, you are correct. I meant that if it's encrypted, you won't be able to decode it easily