I see in Fabook, I don't read all but I think is free , OpenSource, or both.
GIMP
http://www.gimp.org.es/
SumoPaint
https://www.sumopaint.com/
mtPaint
http://mtpaint.sourceforge.net/
Photopea
https://www.photopea.com/
Pixilart
https://es.pixilart.com/draw/max-d514c29072e846b
GraphicsMagick
http://www.graphicsmagick.org/
Piklr
https://pixlr.com/
Canva
https://www.canva.com/es_es/editor-fotos/
Photo Raster
https://photoraster.com/
Paint.net
https://www.getpaint.net/
Pixelitor
http://pixelitor.sourceforge.net/
GrafX2
http://pulkomandy.tk/projects/GrafX2
* * * * * * * * * * * * * * * * * * *
EDITORES DE GRÁFICOS VECTORIALES
InkScape
https://inkscape.org/es/
Boxy SVG
https://boxy-svg.com/
Vectr
https://vectr.com/
* * * * * * * * * * * * * * * * * * *
EDITORES DE PINTURA DIGITAL
Krita
https://krita.org/es
MediBang Paint
https://medibangpaint.com/es/pc/
* * * * * * * * * * * * * * * * * * *
MODELADO 3D
Blender
https://www.blender.org/
MakeHuman
http://www.makehumancommunity.org/
3D Slash
https://www.3dslash.net/index.php
Clara.io
https://clara.io/
Daz Studio
https://www.daz3d.com/
Autodesk Meshmixer
http://www.meshmixer.com/
Sculptris
http://pixologic.com/sculptris/
* * * * * * * * * * * * * * * * * * *
EDITORES DE GRÁFICOS VOXEL
MagicaVoxel
https://ephtracy.github.io/
Cubik Studio
https://cubik.studio/
Hexels
https://marmoset.co/hexels/
VoxEdit
https://www.voxedit.io/
Voxel Max
https://es.voxelmax.com/
Qubicle
http://www.minddesk.com/
Goxel
https://goxel.xyz/
Makers Empire
https://www.makersempire.com/download
VoxelShop
https://blackflux.com/node/11
Dot Modeler
http://www.shionn.org/dotmodeler
Sproxel
http://sproxel.blogspot.com
* * * * * * * * * * * * * * * * * * *
EDITORES DE SPRITES, TILESETS Y MAPAS
Aseprite
https://www.aseprite.org/
Tiled Map Editor
https://www.mapeditor.org/
GraphicsGale
https://graphicsgale.com/us/
Moai
http://members.allegro.cc/sirocco/nav_mo.htm
IDraw Chara Maker 3
http://tsukuru.pl/index.php?link=programy/iDraw
Mappy Editor
http://tilemap.co.uk/mappy.php
Ogmo Editor
http://www.ogmoeditor.com/
Pixela
https://2ddentertainment.com/products_pag/p0006.htm
Pyxel Edit
https://pyxeledit.com/
tIDE
https://archive.codeplex.com/?p=tide
Tilesetter
https://tilesetter.org/
Tile Studio
http://tilestudio.sourceforge.net/
A nicely curated list, thank you Mentalthink!
Thank you.
ad maiora