SMEd is a free, open-source map editor platform which features:
+ Multi-layer 2D Map Editor with support for free-form drag-and-drop placement of entities and images across multiple layers.
+ Integrated Box2D physics allows entities to interact based on user-defined entity models and joints.
+ Entity Editor for defining game entities using images, models, and other customizable properties.
+ 2D Model Editor makes it easy to create models for use in rendering and physics body definition.
+ Image, Entity, and Model Palettes: simply drag-and-drop to the editor
+ XML file formats for easy parsing by your game engine.
SMEd is available for Linux, Mac OS X, and Windows.
SMEd requires an OpenGL 2.0 capable graphics card.
Java is required to run SMEd.
SMEdParser is a free c++ SMEd project parsing library.