tool category   
  design and illustration 

Krita

free and open source drawing and animation tool
Gimp
free and open source image editor
Photopea
free browser based image editor


DitherPaint
free browser based tool for pixel art

Pixilart
free browser based tool and mobile app for pixel art and animation

Inkscape
free and open source vektor editor

Method Draw
free and open source SVG editor for the web, you can use it online without signing up
Repper
free trial of a browser based pattern maker