How to implement real-time collaboration features like Google Docs?
I am working on a document collaboration tool and need to implement real-time editing where multiple users can edit the same document simultaneously. I have researched CRDTs and Operational Transformation but I am not sure which approach is better for my use case.
The application needs to support rich text editing, cursor presence awareness, and conflict resolution. We expect up to 20 concurrent editors per document.
What technologies and algorithms would you recommend? I have seen libraries like Yjs and Automerge. Are they production-ready? What about the WebSocket infrastructure needed to support this?
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I have built two collaborative editing applications and strongly recommend the CRDT approach with Yjs:
Why CRDTs over OT: CRDTs are mathematically guaranteed to converge without a central server arbitrating conflicts. This means better offline support and simpler server architecture. OT requires a central server to transform operations in order.
Tech Stack: Use Yjs for the CRDT implementation - it is production-ready and battle-tested. Pair it with TipTap or ProseMirror for the rich text editor. For WebSocket infrastructure, use the y-websocket provider or Hocuspocus for a more feature-rich solution.
Scaling: For 20 concurrent editors, a single WebSocket server handles it easily. For larger scale, use Redis pub/sub to synchronize multiple WebSocket servers.
A few additional practical tips from our implementation:
Cursor Presence: Yjs has a built-in awareness protocol that handles cursor positions and user presence. It is very efficient and works out of the box with the y-websocket provider.
Persistence: Store document state as Yjs binary updates in your database. This is much more efficient than storing the full document state on every change. You can compact updates periodically.
Conflict UX: Even though CRDTs resolve conflicts automatically, make sure to show users what changed. Highlight recent edits by other users briefly so people understand the collaborative context.