PhotoQt is a simple, yet powerful and good looking image viewer, written in C++/Qt, published as open-source, and completely free. Developed by Lukas Spies
License: Open Source
Ristretto is a lightweight image viewer focused on speed and efficiency, making it ideal for users who need basic viewing and organizing features. In contrast, PhotoQt offers more comprehensive editing tools and a customizable interface, catering to those who require advanced image manipulation capabilities.