Applications:
Ibispaint X (Free on SmartPhones – Advertisements are mostly banners, but may be pop ups rarely, but do get in the way of brushes, even if you can recreate them),
Krita (Free on Desktop, requires a drawing tablet of some kind though).
 
Brushes:
Ibispaint has free brush customisation, and while some brushes are unique in shape, a lot are just the dip pen (which is free) modified, so it doesn’t cost an advertisement to customise those (and it creates a new pen rather than permanently changing the original),
Ibis also has user created brushes allowed to be shared Via QR code, and these can be found very easily through Pinterest – an art showcase app/website, and the one linked is only one example of these collections,
Krita has a devoted location for brushes on the website, made by other artists, and you can make your own too.
Reference Websites:
Pinterest can be used for this too, as other people’s art can be used as reference. Plus, they share reference images (images used to base a pose or design off of) Again, this is only one collection of these examples,
PosemyArt is a website with 3d models you can move that allow for creation of pose references for various body types, included are multiple premade poses, but you can pose your own. Bear in mind that this may slow down lower-end devices,
Heroforge is a website where you can create miniature figures, however, I personally use this for references for outfits, as it has a large set of cosmetic items. Instead of buying it, you can just screenshot the finished design. Bear in mind that this may slow down lower-end devices.
