These improvements came in the wake of decreasing market share to Google Chrome, as well as concerns that its performance was lapsing in comparison. Mozilla support center states that Mozilla announced a project known as Quantum in 2016, which sought to improve Firefox’s Gecko engine and other components in order to improve Firefox’s performance, modernize its architecture, and transition the browser to a multi-purpose model. I will show you how to downgrade Firefox version. Firefox has an updated version, just in case you are not comfortable with the updated version and you would love to get back to your previous version. Its sibling, Firefox for Android, is available for Android. Firefox is available for Windows, Mac OS, Linux, and BSD operating systems. Mozilla Firefox is a free and open-source web browser developed by Mozilla Foundation and its subsidiary, Mozilla Corporation.