How to decode Base64 in C#?

Question

JavaScript

I send a string of Base64 format by Ajax to the server. It comes there in the format {image=data%3aimage%2fpng%3bbase64%2ciVBOR(There are a lot of characters here)kSuQmCC}
Standard function Convert.FromBase64String(s); can't understand this line. What needs to be cut/changed in the line above so that it can be decoded?

Answer 1

I cut out the extra characters at the beginning of the line and it all worked.

Answer 2

It's not exactly Base64 read it . You need to use for example this way

Answer 3

urldecode in php analogue