User Interface (UI) – The Firefox User Interface (UI) is simple and very easy to navigate around.A minimum of 512 MB of RAM is necessary for smooth usage of Firefox.A Pentium 4 Processor is recommended for using Firefox.However, 64bit versions of Firefox only work on 64bit Windows devices. Firefox works on Windows XP and higher.Best of all, Firefox is freeware, that is it is completely free to download and use, but unlike open-source software, you cannot see the source code for freeware. Firefox is also full of many features and tools, all of which make your browsing experience easier and more productive. The application offers a smooth and streamlined experience. Mozilla Firefox is a web browser with sleek and easy to use user interface (UI). Looking for a free to use a web browser that is stacked with features? Well then look no further as Mozilla Firefox is the application for you.