Krita is a free, open-source raster graphics editor written in C++ and Qt, released on June 21, 2005, by the Krita Foundation. It was mainly developed as an illustration program, but it does have built in capabilities for 2D animation.
It is possible to create a fully fledged 2D animation using this software; however, you would have to overcome some limitations, such as Kitra not having a V-Cam and generally lacking features to aid in animating. Some of the benefits of using Kitra are that it has built-in vector tools and is possible to open PSD files. It also makes creating 2D raster animations easier.
Regardless, this is a decent starting point if you want to do 2D animations, especially shorter ones.
UI[]
User experience design[]
Krita's UX was designed with graphics tablet users in mind. It uses a combination of pen buttons, keyboard modifiers, and an icon-based HUD to ensure frequently used functions can be accessed by fewer clicks, without the need to search through text-based menus.
Most-used drawing commands can be accessed via touch by combining keyboard modifiers with pen/mouse buttons and gestures.