• The newest version of the Google Chrome extension 

• macOS Sierra

To check which macOS your device is running, please have a look at the article in Apple support.

Please be aware that macOS Sierra is the minimum requirement, but if you find yourself running an earlier version of macOS and you do not want to fully update your device to the newest version, you can upgrade to only macOS Sierra on this official Apple website.

Thereby, you could still test with Userbrain but don't have the hassle of running the newest update on your device in case you are not a fan of that idea!