I wrote a user script that allows you to get Twitch's OAuth scopes programmatically.
If you're developing an application that makes it easier to work with the Twitch developer API's, you may find it useful to have all possible scopes.
How does it work?
Get the Code
You just need to install the script and visit the page. You can copy the JSON from the console.
After installing the script, you can check your console and you should see the output in a table and in JSON.