paint tool sai to draw the first frame and all key frames, fire alpaca to animate, and gimp to scale up and save as a gif.

Gimp and fire alpaca are free, and they are the only two of these you need to do what i do. The minimum is just gimp, but animating in that is a pain. You dont even need a mouse if you are working small scale, i usually go 100x100 or 200x200 depending on what i make in terms of canvas size, the smaller it is, the easier it is to handle with just a mouse.

Thank you very much