Adding Multiplayer to Your Browser Game: WebSocket Basics

October 9, 2026 · FarmHeart

Single-player browser games are fun. Multiplayer browser games are addictive. WebSockets make real-time multiplayer possible without plugins or downloads.

How WebSockets Work

Unlike HTTP (request → response), WebSockets keep a persistent connection open between the browser and server. Either side can send data at any time. This is what makes real-time games possible — the server can push game state updates 30–60 times per second.

Basic Architecture

Client sends input: player presses left arrow → client sends {"action":"move","dir":"left"} to server
Server processes: validates the move, updates the game state, checks for collisions
Server broadcasts: sends updated positions/state to ALL connected clients
Clients render: each browser draws the updated game state

Server Options

Node.js + ws: the most common choice. Simple, fast, well-documented
Socket.io: adds auto-reconnection, rooms, and fallbacks. Slightly more overhead but easier to build with
Colyseus: game-specific multiplayer framework. Handles rooms, state sync, and matchmaking out of the box

Common Pitfalls

Trusting the client: never let the client decide game outcomes. Always validate on the server. Clients can be hacked
Sending too much data: only send what changed, not the entire game state every frame
Not handling disconnects: players lose connection constantly. Handle reconnection gracefully
Ignoring latency: a 200ms round trip feels terrible. Use client-side prediction (move locally, correct when server responds)

Start simple: build a turn-based multiplayer game first (tic-tac-toe, card game). Then tackle real-time. The networking concepts are the same, but turn-based is much more forgiving of latency.