Customizable privacy conscious web browser for power users patched for better integration with KDE Plasma.
It works great on other desktop environments too.

Waterfox focuses on giving users choice while also helping make the world a better place. Watefox is partners with Ecosia, a search engine that plants trees with its generated revenues. The browser itself is focused on power users, which lets you make the important decisions. There is no plugin whitelist, you can run whichever extensions you like and absolutely no data or telemetry is sent back to Mozilla or the Waterfox project.

Waterfox is powered by Mozilla Firefox source code.

Note: KDE integration features works best with kwaterfoxhelper and plasma-browser-integration packages installed together with Plasma Integration extension.