The Nota text editor features a simple interface by default.
Gnome Text Editor
A simple text editor.
pulsar
A Community-led Hyper-Hackable Text Editor.
Thorium Reader
Thorium Reader is an easy to use EPUB reading application.
Linwood Butterfly
Powerful, minimalistic, cross-platform, opensource note-taking app.
Core PDF
A simple lightweight PDF viewer.
Mousepad
Mousepad is a simple text editor for Xfce .
sleek
sleek is a todo app based on todo.txt, free and open-source.
Dupeguru
dupeGuru is a cross-platform (Linux, OS X, Windows) GUI tool to find duplicate files in a system.
Corepad
A document editor for C Suite.