draw.io
draw.io – free and open source, cross-platform program for creating diagrams and schemes , official desktop client diagrams.net
GNOME Calculator
GNOME Calculator is a free and open source, simple yet powerful calculator with advanced, financial, and programming modes
AnyMeal
AnyMeal is a free and open source recipe management software
Norka
Norka is a free and open source continuous text editor with Markdown support
Heimer
Heimer – free and open source, multiplatform and simple software for creating mind map, diagram, and note-taking tool
VYM (View Your Mind)
VYM (View Your Mind) – free and open source, multi-platform tool to generate and manipulate maps which show your thoughts
Freeplane
Freeplane – free and open source, multi-platform software for creating mind map, as well as knowledge management
XMind
XMind – free and cross-platform software for creating mind maps
FreeMind
FreeMind – free and open source software for creating mind map
Kate
Kate – free and open source, multiplatform and advanced text editor for KDE