Dungeon Manager seeks to provide a free and open-source management system for game-runners (Dungeon Masters) for the tabletop roleplaying game Dungeons and Dragons™, allowing them to prepare a dungeon (or series of rooms) with collections of monsters (either custom-defined or provided from the base-game) and rooms, and allow them to dynamically change the rooms, including the maps and the monsters present in the rooms. The project is implemented as a client-server web application using RESTful API architecture design principles, and interfaces with a MongoDB database to hold user, dungeon, room, monster and map information and images. The project is not intended to replace other online play services such as Roll20 or host the game itself, but rather is intended to be used alongside regular play as a resource to the Dungeon Master. Through personal experience and user testing, the project was designed to provide a simple and user-friendly interface. The project was successful in implementing a web application which provides all the functionality described above, and is a promising start for future development in tabletop management web applications.