In today's digital world, real-time collaboration is essential in online document editors (like Google Docs, Notion, etc.). One of the core technologies enabling this collaboration is CRDT (Conflict-Free Replicated Data Type).
This project (or guide) explains:
- What CRDT is and how it works.
- How CRDT can be used to build collaborative document editors.
- How to implement real-time syncing using the Yjs library (a powerful CRDT implementation for JavaScript).
- Advanced concepts like awareness, offline editing, and syncing via WebRTC or WebSocket.
CRDT (Conflict-Free Replicated Data Type) is a data structure designed for distributed systems where concurrent changes are made independently and then merged automatically without conflicts.
- Conflict-free: Concurrent edits never conflict.
- Eventually Consistent: All replicas converge to the same state.
- No Central Server Needed: CRDTs can sync peer-to-peer or server-client.
In collaborative text editing:
- User A types "Hello"
- User B types "World"
- Both changes are merged automatically as "HelloWorld" or "WorldHello" (depending on timestamp/ordering logic).
In online document editors, multiple users might:
- Type, delete, or format text at the same time.
- Add/remove sections.
- Work offline and later sync changes.
CRDT ensures that:
- All updates are preserved.
- Document state remains consistent across users.
- No data is lost or overwritten.
Yjs is a high-performance CRDT implementation that supports shared editing in real-time.
- Shared text editing (
Y.Text) - Real-time syncing with WebSocket, WebRTC, IndexedDB
- Offline support and sync when back online
- Awareness API (user presence, cursors)
- Rich integrations (TipTap, CodeMirror, ProseMirror, Slate, Quill)
# 1. Clone the repo
git clone https://github.com/your-username/yjs-crdt-editor.git
cd yjs-crdt-editor
# 2. Install dependencies
npm install
# 3. Run development server
npm run dev