Tiled
Flexible level editor
...It can be used to create maps of any size, with no restrictions on tile size, or the number of layers or tiles that can be used. Maps, layers, tiles, and objects can all be assigned arbitrary properties. Tiled's map format (TMX) is easy to understand and allows multiple tilesets to be used in any map. Tilesets can be modified at any time. Tiled is a general purpose tile map editor for all tile-based games, such as RPGs, platformers or Breakout clones. Tiled was originally written in Java. In 2008, work began to develop a faster, better looking, and easier-to-use version of Tiled based on the Qt framework. ...