Apps similar to MMapper include Tiled Map Editor, which is free and open source. Other options are LDtk, Dungeondraft, OGMO Editor and MapperMate. In total there are nine Game Development Tools like MMapper for Mac, Windows, Linux and the web.
Tiled is a general purpose tile map editor. It's built to be easy to use, yet flexible enough to work with varying game engines, whether your game is an RPG, platformer or Breakout clone. Tiled is free software and written in C++, using the Qt application framework.
Netherlands
EU
LDtk (Level Designer Toolkit) is a modern and open-source 2D level editor, specifically designed for indie devs.
FranceEU
United States
OGMO Editor is a free, open source, project oriented level editor made for indie game developers by indie game developers. Beyond using Tile Layers to create levels from a tileset, use Decal Layers to freely place, scale, and rotate images to decorate your level, Entity Layers...
Canada
Free online tilemap editor for 2D games. Create, edit, and export game maps directly in your browser with JavaScript and Godot support.
United States
Drag and drop tile based mapping program. Multiple layers, create and import your own tilesets, scale for printing and many more features.
Tilesetter is a tileset generator & map editor tool - Create your whole tileset instantly. Generate complete tilesets from base images. Build and export levels directly to Unity, Godot and GameMaker Studio 2.
Map-making software for creating tactical-scale top-down battlemaps for RPGs, with a large library of ready-to-use mapping content Add-Ons (including 50 free ones!). Also works with your own artwork/bitmaps, via drag-and-drop.
United States
Designed with simplicity in mind, Sprite Fusion offers the essential features set like autotile, multiple level designs, layers, tilesets imports, and a variety of supported exports:
