CoffeeMUD is designed to be a flexible and extensible MUD engine with a large array set of customizeable gameplay and editing features. The project's goal is to provide a basis for the creation of various fantasy games for both the technically inclined and others.
The last version of CoffeeMUD released by Bo Zimmerman is 5.9.8 as of Jul 20, 2019. 
CoffeeMUD is written completely in the Java programming language. CoffeeMUD 5.9.8 has over 950k source code lines, excluding comments and blank lines.
It includes world building facilities both from within the game, and from the built-in web site. There are also several scripting languages for game events, including MOBPROG and Rhino.
The engine was originally designed for game building to be done by creating in-game objects in Java and integrating them using the online-creation abilities. This was later extended to allow all aspects of game creation to occur online.
CoffeeMud began in February 2000 as an attempt to duplicate the look and feel of ROM in the Java programming language. Its name, like many of the engine components, is a pun on the word Java.
Version 1.0 was released in March 2001, though the engine's features didn't start growing in earnest until 2003, when new revisions began appearing every 1–3 weeks through early 2007. Since 2007, new revisions have been less frequent.