Pyxel Edit: pixel art and tileset editor
Pyxel Edit is a pixel art editor designed to make it fun and easy to make tilesets, levels and animations.
Made for tilesets
Pyxel Edit is built around tiles: draw in one tile and every copy of it updates instantly, so you can sketch a whole level mock-up and polish the tileset in place. Tile instances can be rotated and flipped while still referencing the same tile data, and the tilemap exports to XML, JSON or plain text for quick game prototyping.
It also does frame-by-frame animation with onion skinning, exports sprite sheets and animated GIFs, and can import existing tileset images or mock-ups and identify all the unique tiles automatically. See the full feature list, get the beta or the free version, or browse the community forum archive for artwork and tips from other users.