Buho is a note-taking app. Buho will let you take quick notes, save links, create books and pages for taking classes notes.
It is free and multi-platform, and open source under the LGPL v3 License.
Index is made with Mauikit.
MauiKit A free and modular front-end framework for developing fast and compelling user experiences. It helps to quickly build UIs that follow the Maui HIG and bring ready to go tools for different platforms, such as Android and Linux.
MauiKit and the Maui Applications are made by the Maui project (which is a part of the KDE project) and Nitrux Latinoamericana S.C.