LibreSprite Animated Sprite Editor and Pixel Art Tool
LibreSprite is a free and open source animated Sprite and pixel editor application for Linux, Windows and MacOS. Using LibreSprite you can create 2D retro style sprite and pixel art graphics for video and games. it comes with real time animation previews, onion skinning and you can edit multiple sprites at once. Some other useful features are build-in palettes editor and layers & frames support, tiled drawing mode and you can also import and export sprite sheets. It is released under GNU General Public License v2.0.