These APIs include:
Multiplayer Assign API, for automatically assigning end users to worlds, creating new worlds as appropriate.
Multiplayer Project API, for specifying, at a project level, how multiplayer worlds are configured.
Multiplayer World API, for manually linking end users together in multiplayer worlds, and for creating runs for each world.
Presence API is used by Epicenter internally to track whether end users are online or offline; notifications are sent to the group channel and world channel. Additionally, notification is sent to the presence channel, which is an Epicenter.js abstraction: special type of group channel that only listens to presence notifications. It is used primarily for multiplayer games.