Krita

Krita is an open source drawing, painting and animation application designed for illustrators, concept artists, comic book creators, animators, game artists, matte painters and more. Krita is used daily by artists all over the world from professionals, to students, to enthusiastic hobbyists.

Krita offers many features, including industry standards and innovative designs, which make painting more fun and productive. There are powerful brush engines for sketching and painting, stabilizers for smooth freehand inking, assistants for constructing a complex scene, a distraction-free canvas-only mode for painting without clutter, multiple types of layers and masks for non-destructive editing and, frankly, too many other features to list! You can also exchange files with other applications in a variety of different formats.

Another thing that makes Krita truly stand out is that it's being developed in coordination with an international community of open source ...