Krita

Krita is a free, Open-Source painting tool designed for concept artists, illustrators, matte and texture artists, and the VFX industry. Krita has been in development for over 10 years and has had an explosion in growth recently. It offers many common and innovative features to help the amateur and professional alike.

Features:

• User Interface - An intuitive user interface that stays out of your way. The dockers and panels can be moved and customized for your specific workflow. Once you have your setup, you can save it as your own workspace. You can also create your own shortcuts for commonly used tools.
• Brush Stabilizers - Have a shaky hand? Add a stabilizer to your brush to smoothen it out. Krita includes 3 different ways to smooth and stabilize your brush strokes. There is even a dedicated Dynamic Brush tool where you can add drag and mass.
• Pop-up Palette - Quickly pick your color and brush by right-clicking on the canvas. You can also use Krita’s tagging system to swap out the available brushes that are displayed. The ring outside of the color selector contains the most recently used colors. These settings can be configured through the preferences.
• Brush Engines - Customize your brushes with 9 unique brush engines. Each engine has a large amount of settings to customize your brush. Each brush engine is made to satisfy a specific need such as the Color Smudge engine, Shape engine, Particle engine, and even a filter engine. Once you are done creating your brushes, you can save them and organize them with Krita’s unique tagging system.
• Wrap-around Mode - It is easy to create seamless textures and patterns now. Press the ‘W’ key while painting to toggle wrap-around mode. The image will make references of itself along the x and y axis. Continue painting and watch all of the references update instantly. No more clunky offsetting to see how your image repeats itself.
• Resource Manager - Import brush and texture packs from other artists to expand your tool set. If you create some brushes that you love, share them with the world by creating your own bundles. Check out the brush packs that are available in the Resource area.

Note: While the software is classified as free, it is actually donationware. Please consider making a donation to help support development.