Which KDE web browser was formerly known as QupZilla?

The KDE web browser formerly known as QupZilla is Falkon.

QupZilla began as an independent, lightweight Qt browser project in 2010. It was first written with Python and PyQt, then substantially rewritten in C++ using the Qt framework. Earlier releases used QtWebKit, but the project later moved to QtWebEngine, which is based on Chromium technology.

In 2017, QupZilla moved into the KDE community and received a new name: Falkon. The first Falkon release arrived as version 3.0 in 2018, reflecting the rebranding rather than a completely unrelated browser. That history is why QupZilla and Falkon are often treated as the same project across older downloads and documentation.

Falkon is easy to confuse with Konqueror because both are associated with KDE. Konqueror is an older, broader KDE application that can handle file management as well as web browsing; Falkon is focused specifically on browsing.