Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Astropad - Astropad is a free form drawing tool designed from the ground up to take advantages of the features offered by an iPad.
Artrage - A simple but lovely natural media painting and sketching program.
Paper by WeTransfer - A collection of creative prompts
Procreate - Procreate is the most powerful and intuitive digital illustration App available for iPad®.
Milanote - Milanote is a note taking app for creative work.