A real-time collaborative note-taking web application (Google Docs Lite), where multiple users can edit a note simultaneously, share it, and view version history.

{
  _id,
  name,
  email,
  passwordHash,
  notesSharedWith: [noteId],
  createdAt
}

{
  _id,
  title,
  content, // plain text or Quill Delta
  owner: userId,
  collaborators: [userId],
  versionHistory: [
    { editedBy, timestamp, diff }
  ],
  createdAt,
  updatedAt
}

{
  _id,
  noteId,
  userId,
  content,
  timestamp
}

{
  noteId: [userId1, userId2, ...]
}

• POST /api/auth/register
• POST /api/auth/login
• GET /api/auth/me

• GET /api/notes/
• POST /api/notes/
• GET /api/notes/:id
• PUT /api/notes/:id
• DELETE /api/notes/:id

• POST /api/notes/:id/collaborators
• GET /api/notes/:id/collaborators

• GET /api/notes/:id/comments
• POST /api/notes/:id/comments

Each note = one socket room. All collaborators receive real-time updates.

• ✅ JWT auth (stored in HTTP-only secure cookies)
• ✅ Password hashing with bcrypt
• ✅ Rate limiting with express-rate-limit
• ✅ Input sanitization to prevent XSS
• ✅ CSP headers using helmet
• ✅ Socket middleware to verify auth before joining a room

• Save full content every X seconds (autosave)
• Store diffs via diff-match-patch if needed
• versionHistory[] on note model

1. Model MongoDB schemas for User, Note, Comment
2. Create RESTful APIs for auth, CRUD, sharing
3. Implement WebSocket logic via Socket.IO for real-time collab
4. Set up middleware for secure auth (JWT & socket)
5. Frontend handles:
   • Editor (Quill)
   • Collaboration (socket)
   • State management (Zustand/Context)
6. Add autosave, versioning & typing indicators
7. Deploy frontend/backend separately with environment configs

This app combines:

• CRUD + Real-time Sync
• Role-based collaboration
• Scalable backend & socket handling
• Secure auth & data access
• Version control & UX enhancements