Vivaldi features the ability to “stack” and “tile” tabs, annotate web pages, and add notes to bookmarks. Furthermore, users can place digital bookmarks on a “speed dial” page for quick access and harness “quick commands” to search bookmarks, browsing history, open tabs, and settings.] Vivaldi is built around and based on web technologies such as HTML5, Node.js, React.js, and numerous NPM modules. As of Technical Preview 4, Vivaldi also supports numerous mouse gestures for actions like tab switching and keyboard activation. Vivaldi can also be set to a “Chromeless UI”, which gives users more screen real-estate and the ability to focus on a single page without distractions. To accommodate users who prefer to use a large number of tabs at the same time, Vivaldi supports hibernation for both individual tabs and for tab stacks, freeing resources while the user does not actively use those tabs.