Hello,
When I export my WebGL game it works fine offline, but when I transfer it via FTP to my web server and play from there, I get the following error:
"
An error occured running the Unity content on this page. See your browser JavaScript console for more info. The error was:
SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data"
Any help would be greatly appreciated! 
I guess you donβt really need a solution any more but there was already a thread like this with a solution posted. The original answer can be found behind this link and a copy of the code from that thread is also posted below:
http://answers.unity3d.com/answers/1348064/view.html
To make this code work, you need to create a web.config file with the following code in it.
Then place the file next to your index.html on your server.
This works for me with Unity 5.6.1f1.
<configuration>
<system.webServer>
<staticContent>
<!-- Unity 5.6 -->
<mimeMap fileExtension=".json" mimeType="application/json" />
<mimeMap fileExtension=".unityweb" mimeType="application/binary" />
<!-- Unity 5.x -->
<mimeMap fileExtension=".data" mimeType="application/binary" />
<mimeMap fileExtension=".mem" mimeType="application/binary" />
<!-- Unity 5.3 -->
<mimeMap fileExtension=".datagz" mimeType="application/binary" />
<mimeMap fileExtension=".jsgz" mimeType="application/binary" />
<mimeMap fileExtension=".memgz" mimeType="application/binary" />
</staticContent>
</system.webServer>
</configuration>