Base64 Javascript vs. Base64 C#.Net and JSON calls

Does anyone have a good working example of how to send Base64 to EvoStream via JavaScript, JSON, C# .aspx page from IIS web server? Does EvoStream accept Base64 C#.Net for sending request to EvoStream server? I noticed Base64 C# method is slightly different than Base64 JSON method, not sure why this is so. Base64 C# method seems to be off on the last character in the Base64 showing ‘=’ sign when it is ‘g’ character with JSON method. I’ve used both System.Text.ASCIIEncoding.ASCII.GetBytes(text_string_value) and System.Text.UnicodeEncoding.UTF8.GetBytes(text_string_value). Any suggestions? Thank you in-advance. RED