How I Built a Socket.IO v4 Client for Unity from Scratch (with WebGL Support)

Every Unity multiplayer developer hits the same wall. You've got a Node.js backend running Socket.IO. Your web client connects in three lines. Then you open the Unity docs, search the Asset Store, and spend two hours realising that the Unity side of this equation is... a mess. That's where I was. And it's why I built socketio-unity . The State of Socket.IO in Unity (Before This) When I started, the options were grim: Paid assets with no source code and no way to fix bugs yourself Abandoned repos targeting Socket.IO v2 or v3, incompatible with the current protocol WebGL support that was either broken or missing entirely — and WebGL multiplayer is huge if you want browser-based games I needed something open-source, Socket.IO v4, and WebGL-verified. It didn't exist, so I built it. The Architecture (High Level) Before diving into the hard part, here's the shape of the library: Socket.IO Server ↓ ITransport ←── WebSocketTransport (Standalone) ←── WebGLWebSocketTransport (Browser) ↓ EngineIO