VivaldiFox - An add-on that allows colouring Firefox in a Vivaldi style fashion
Responsive Viewer - View multiple screen dimensions in one view
ShadowFox - This project aims at creating a universal dark theme for Firefox while adhering to the modern...
Responsinator - Designed to test responsive websites on different devices.
Firefox Color - Build Beautiful Firefox Themes
Responsive Website Test - Test any website on desktop, mobile, and tablet