Vivaldi is a free, highly customizable web browser first released on April 6, 2016. It is developed by Vivaldi Technologies, a company co-founded by Jon Stephenson, a co-founder and former CEO of Opera Software. He launched Vivaldi in response to community displeasure with changes to the Opera web browser. With Vivaldi, he wanted to create a browser that recaptures the minimalism and customizability of the original Opera.
The Vivaldi browser UI is designed to "get out of the way." It features buttons and menus that are unobtrusive, and an optional "Chromeless UI" for maximizing screen real estate. Like the original Opera, the Vivaldi background color can change to adapt to the color scheme of the current website. The browser also offers mouse gestures, enabling the user to control the browser by moving the mouse in certain ways.
The source code of Vivaldi is available for anyone to view or audit for security purposes.