Real-Time Collaborative Editor Backend

A scalable, conflict-free real-time collaborative editing backend — inspired by Google Docs — built with Node.js, Socket.IO, Redis Pub/Sub, and MongoDB. Supports multiple concurrent users editing the same document with Operational Transform (OT) conflict resolution and multi-instance horizontal scaling.

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Features

• Real-Time Text Editing
• Operational Transform (OT) conflict resolution
• Redis Pub/Sub cross-server sync
• MongoDB persistence with versioning
• Supports multi-character insert/delete/paste
• Ready for horizontal scaling and deployment

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Tech Stack

Layer	Tech
Server	Node.js + Express
WebSocket Engine	Socket.IO
State Sync Engine	Operational Transform (Custom)
Pub/Sub Broker	Redis
Database	MongoDB + Mongoose
Frontend (Basic)	HTML, CSS, JS

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Getting Started

1. Clone the Repository

git clone https://github.com/yourusername/collab-editor-backend.git
cd collab-editor-backend

2. Install Dependencies

npm install

3. Start Redis & MongoDB

Using Docker:

# Redis
docker run --name redis -p 6379:6379 redis

# MongoDB
docker run --name mongo -p 27017:27017 mongo

Or install them locally if Docker is not preferred.

4. Run Multiple Servers

# Terminal 1
npx cross-env PORT=3000 node server.js

# Terminal 2
npx cross-env PORT=3001 node server.js

Open http://localhost:3000 and http://localhost:3001 in browser tabs to test real-time sync across servers.

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Test It

• Users joining the same docId will see each other’s edits in real time.
• Edits propagate across servers via Redis.
• Operational Transform ensures conflict-free syncing.

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Future Plans

• User Authentication & Role-based Access
• Live Cursors & User Presence
• Docker + Docker Compose Setup
• Cloud Deployment on Render / Railway / EC2
• Load Testing with 1000+ simulated users

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Author

Tanishq Parihar B.Tech CSE (Data Science), IIIT Nagpur LinkedIn | GitHub

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License

This project is licensed under the MIT License.