http://free-tex-packer.com/, source @ https://github.com/odrick/free-tex-packer
Sprite sheets for games and sites
https://www.mapeditor.org, source @ https://github.com/mapeditor/tiled
Tiled is a free and open source, easy to use, and flexible level editor.
https://www.codeandweb.com/texturepacker
Pack your sprite sheets in seconds. Use TexturePacker to create sprite sheets from your images. Fast. Optimized. Easy to use. Create sprite sheets and optimize your game graphics.