Mipui has real-time collaboration between multiple authors. In particular, no textures are used, instead opting for a symbolic approach.

Mipui employs a limited but expressive set of tools, avoiding the bloat that exists in some other map editors while still remaining rich enough for most everyday gaming needs. No registration is neccessary, and there's nothing to download or install.

Mipui is a free and open-source collaborative web application for creating, editing and viewing grid-based maps for tabletop or role-playing games.