The extension (currently available for Chrome only; Firefox and IE support are on the way) is easy to use. When you’re visiting a web page that has related (community curated) rebuttals, you’ll see a notification of those rebuttals on the extension’s button. Click it to browse, open and read those rebuttals. What’s the point?
You should use rbutr to break out of your Filter Bubble, the forced state of being constantly delivered the same one sided perspectives from search engines and social tools which are designed to only give you more of what you want and already believe, rather than what you need in order to stay informed. Facts aren’t simple. The truth is usually more complicated than anyone cares to admit. Rigorous discussion is the best tool available to keeping yourself informed and rbutr allows you to follow the discussion rather than just being sold one side or the other.
Rbutr requires that you sign up for an account before you install the extension. (The account allows you to submit links you stumble onto as rebuttals.) The service is free to use, and definitely seems worth a look.