Vivaldi for Mac is a new, feature rich web browser that combines an Opera-like interface with a Chromium open-source platform. Vivaldi for Mac is very similar to the Opera browser in many ways. Google Chrome for Mac. To open Chromium for the first time, do the following: Double click on the file chrome-mac.zip file on your computer to unzip it. Double click on the unzipped folder to open it. You should see the Chromium.