Mastering Real-Time Collaborative Editing with Yjs and WebSockets

Building a collaborative editing tool — like Google Docs — is an ambitious but incredibly rewarding project. In this article, we'll explore how to achieve real-time collaboration in the browser using Yjs, a CRDT (Conflict-free Replicated Data Type) library, combined with WebSockets to sync shared state across users.

Why Yjs?

Yjs is a powerful framework for real-time collaboration. It handles conflict resolution, offline editing, and syncs efficiently. Unlike operational transformation (OT) algorithms, Yjs uses CRDTs that naturally converge without the need for a central server to resolve conflicts.

Step 1: Setting Up the Project

mkdir yjs-collab
cd yjs-collab
npm init -y
npm install express ws yjs y-websocket

Step 2: Creating a WebSocket Server

// server.js
const http = require('http');
const WebSocket = require('ws');
const setupWSConnection = require('y-websocket/bin/utils.js').setupWSConnection;

const server = http.createServer();
const wss = new WebSocket.Server({ server });

wss.on('connection', (ws, req) => {
  setupWSConnection(ws, req);
});

server.listen(1234, () => {
  console.log('WebSocket server running on ws://localhost:1234');
});

Step 3: Setting Up the Frontend

// index.html



  Yjs Collaborative Editor


  
  



Step 4: Testing It Out
Open the HTML file in multiple tabs or browsers. All users will see real-time updates as they type into the shared textarea.
Advanced Ideas
    
  
  • Integrate with CodeMirror or Monaco Editor for rich collaborative coding
    • 
  
  • Add user awareness (cursors, names, colors) via y-protocols/awareness

    • 
  
  • Persist shared state with LevelDB or MongoDB
    • 
  
  • Integrate auth for permissioned access to documents
    • 

Conclusion
Yjs and WebSockets provide a powerful foundation for building collaborative tools with minimal complexity. Whether you're building a shared editor, a whiteboard, or a note-taking app — this tech stack offers the scalability and flexibility you need.
If this guide helped you, consider supporting my work: buymeacoffee.com/hexshift