What's included? Basically there are some key features which I lacked most on the Duolingo web app and which absence made me to develop this addon, namely

• night mode,
• streak notifications/reminders,
• printing lesson notes,
• writing custom lesson notes and
• quick courses overview.

There are also many other features that are already implemented or are planned in the near future. Don't forget to visit Duolingo Boost's official webpage to learn more about it. New in version 0.4.1 - Fix login issues in Firefox. #11 #15 - New update notification popup window.