Tabletop RPG Map editor 2 - RPG Map II is a “tabletop RPG” oriented map maker, created with the “keep it clean & simple” philosophy in mind.
Tiled Map Editor - Tiled is a general purpose tile map editor.
Campaign Cartographer - Campaign Cartographer is the leading map making software for games (RPGs, miniatures and wargaming).
Tilesetter - The tileset designing software.
Inkarnate - A free-form map editor for role-playing games, focusing on overland and continental maps.
Mipui - An online grid-based map editor for games, with real-time collaboration.