Multiplayer Synchronization in Decentraland

Decentraland runs scenes locally in a player's instance of the explorer. By default, players are able to see each other and interact directly, but each player interacts with the environment independently. Changes in the environment aren't shared between players by default.

To sync any changes in the scene state, SDK7 uses CRDT-based synchronization.

Runtime constraint: Decentraland runs in a QuickJS sandbox. No Node.js APIs (fs, http, path, process). Use fetch() and WebSocket for network communication. See the scene-runtime skill for async patterns.

Sync Strategy Decision Tree

Choose the right networking approach based on what you need:

Strategy	Use When	Persistence	Example
`syncEntity`	Shared state that all players see and that persists for new arrivals	Yes — state survives player join/leave, but only as long as at least one player remains in the scene. The state resets as soon as the scene is empty	Doors, switches, scoreboards, elevators
`MessageBus`	Ephemeral events that only matter in the moment	No — late joiners miss past messages	Chat messages, sound effects, particle triggers
`fetch` / REST API	Reading or writing data to an external server	Server-dependent	Leaderboards, inventory, external game state
`signedFetch`	Authenticated requests that prove player identity	Server-dependent	Claiming rewards, submitting verified scores
`WebSocket`	Real-time bidirectional communication with a server	Connection-dependent	Live game servers, real-time chat.

multiplayer-sync

Multiplayer Synchronization in Decentraland

Sync Strategy Decision Tree