Sprite Fusion - Design your game with Sprite Fusion, the ultimate free online tilemap editor. Design 2D games with ease, direclty export to Unity Tilemap and Godot Scenes. Ideal for retro games!
Tile Studio - Complete development utility for graphics of tile based games.
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
LibreSprite - Free and open source program to create animated sprites.
Tiled Map Editor - Tiled is a general purpose tile map editor.
Piskel - Piskel is a website where designers online create sprites or pixel art.