I like working with:
Python programming language http://python.org
XeLaTeX typesetting system http://scripts.sil.org/xetex
Inkscape scalable graphics editor http://inkscape.org
Graphviz structured data visualisation http://graphviz.org
PlantUML diagrams http://plantuml.sourceforge.net
Nuspell spelling checker https://nuspell.github.io
Bootstrap-Flask web front-end https://pypi.org/project/Bootstrap-Flask