If you upload a .json file to your Windows Azure website and try to access it, it would give you a 404 File Not Found error, because the MIME Type of .json is not set by default. This also applies in general to any file that might need a specific MIME Type.
To fix this issue, FTP into your website and upload the following Web.config file which will set the correct MIME types. If you already have a Web.config file in place, just add the below to the appropriate section.
<mimeMap fileExtension=".json" mimeType="application/json" />