Tile Studio - Complete development utility for graphics of tile based games.
VistaCreate - The VistaCreate is a free and global digital platform which is known for sharing, searching, finding, and creating great art.
Tilesetter - The tileset designing software.
PaintCAD - Pixel art image editor, created for full keyboard control of image drawing without mouse using.
LibreSprite - Free and open source program to create animated sprites.
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.