FeatherPad is a lightweight Qt plain-text editor for Linux.
Kate
Kate is a multi-document, multi-view text editor by KDE. It features stuff like codefolding, syntaxhighlighting, dynamic word wrap, an embedded console, an extensive plugin interface and some preliminary scripting support.
Liri text
Liri Text is a cross-platform text editor made in accordance with Material Design.
Marker
Marker is a simple yet robust markdown editor for the linux desktop.
Kwrite
KWrite is a text editor by KDE, based on the Kate’s editor component.
Tiled
Tiled is a general purpose tile map editor for all tile-based games, such as RPGs, platformers or Breakout clones.
Hewula
A general purpose, fast and lightweight editor with a keyboard-centric minimalistic user interface.
I-Notejot
Stupidly simple notes app
I-FUFPDF
DiffPDF is used to compare two PDF files.
i-qtractor
Qtractor is an Audio/MIDI multi-track sequencer application written in C++ with the Qt framework.