I’ve always been fascinated by how multiple people can work together on the same document without stepping on each other’s toes. The magic of real-time collaboration—seeing changes appear instantly as others type—feels like modern sorcery. After building several collaborative applications and hitting numerous synchronization walls, I discovered Yjs and its elegant approach to conflict resolution. Today, I want to guide you through creating your own real-time collaborative editor that scales beautifully.

Have you ever considered what happens when two people delete the same paragraph simultaneously?

Traditional methods often struggle with merge conflicts. Operational transformation requires complex server logic and careful sequencing. Yjs uses conflict-free replicated data types (CRDTs), which ensure all copies converge to the same state mathematically. This means no manual conflict resolution—the system handles it automatically.

Let me show you how simple the core concepts are. We’ll start with basic Yjs setup.

// Initialize a shared document
import * as Y from 'yjs'

const doc = new Y.Doc()
const sharedText = doc.getText('document')
sharedText.insert(0, 'Hello, collaborators!')

// Listen for changes
sharedText.observe((event) => {
  console.log('Change detected:', event.changes)
})

Why does this matter for real-time applications?

Every change becomes a predictable operation. Whether users are online or offline, their edits merge seamlessly when they reconnect. The data structure guarantees consistency without constant server communication.

Now, let’s connect multiple clients. We’ll use WebSockets for real-time updates.

// WebSocket server setup
import { WebSocketServer } from 'ws'
import { setupWSConnection } from 'y-websocket/bin/utils'

const wss = new WebSocketServer({ port: 1234 })
wss.on('connection', (ws, request) => {
  setupWSConnection(ws, request, { docName: 'my-document' })
})

This minimal server handles document synchronization automatically. Each room (or document) maintains its own state, and Yjs manages the complex merging logic behind the scenes.

What about the frontend? Next.js provides an excellent foundation.

// React component using Yjs
import { useYjs } from './hooks/useYjs'

function CollaborativeEditor() {
  const { sharedText, connected } = useYjs('document-id')
  
  const handleChange = (event) => {
    sharedText.delete(0, sharedText.length)
    sharedText.insert(0, event.target.value)
  }

  return (
    <div>
      <textarea 
        value={sharedText.toString()} 
        onChange={handleChange}
      />
      <span>Status: {connected ? 'Connected' : 'Offline'}</span>
    </div>
  )
}

Notice how the textarea reflects shared state? Changes propagate to all connected users instantly. The useYjs hook manages the WebSocket connection and document binding.

But how do we handle disconnections and reconnects?

Yjs stores all operations locally. When a user goes offline, their changes queue up. Upon reconnecting, the system synchronizes missed updates automatically. This offline-first approach ensures no work gets lost.

Let’s add user presence—showing who’s currently editing.

// Tracking active users
const awareness = doc.awareness
awareness.setLocalState({ 
  user: { name: 'Alice', color: '#ff0000' },
  cursor: { position: 42 }
})

awareness.on('change', () => {
  const states = awareness.getStates()
  updateUserList(Array.from(states.values()))
})

Each user’s cursor and selection become visible to others. This creates that familiar collaborative experience where you see teammates typing in real time.

Performance becomes crucial with many concurrent users. Yjs optimizes this through operational compression and efficient data structures. Large documents remain responsive because only changes transmit—not the entire content.

What happens during network latency or packet loss?

The CRDT design handles delayed messages gracefully. Operations remain commutative and associative, so order doesn’t matter. Users might see slight delays, but the final document always matches.

Deployment requires careful planning. I recommend using a managed WebSocket service for production, but for learning, a simple Node.js server suffices. Remember to persist documents to database storage periodically.

Here’s my personal insight after building several collaborative editors: start simple. Implement basic text synchronization first. Add presence features later. The Yjs ecosystem provides excellent building blocks that scale from prototypes to production applications.

Have you considered how you’d implement version history or undo functionality?

Yjs maintains complete change history, enabling features like time-travel debugging. You can snapshot document states or replay operations from any point.

Building collaborative applications teaches important lessons about distributed systems. Network partitions, eventual consistency, and user experience all intertwine. The satisfaction of seeing multiple cursors dancing across a shared document makes the effort worthwhile.

I’d love to hear about your experiences with real-time collaboration. What challenges have you faced? Share your thoughts in the comments below, and if this guide helped you, please like and share it with others who might benefit. Let’s build more connected applications together.