Aseprite is a pixel art tool that lets you create 2D animations for video games.
Features:
Compose sprites using layers & frames as separated concepts.
Create images in RGBA or Indexed color modes.
Open/Save GIF animations, sequence of PNG files, etc.
A timeline where you can copy/move layers, frames, or specific images.
Animation tools: Real-time animation preview, onion skinning, tag frames.
Pixel art tools: shading, pixel-perfect strokes, RotSprite rotation, tiled mode, filled contour.
Export/import sprite sheets.
A command line interface to automate conversion and sprite sheets generation.