Aseprite is a pixel art tool that lets you create 2D animations for videogames.

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
  
• Updates for the whole v1.x series up to v1.9.