Real-Time Sync App with Redis & Socket.IO

A real-time checkbox board where multiple users can toggle checkboxes, and the state is instantly synced across all connected clients. Built with

• 🟩 Node.js
• 🌐 Socket.IO
• 🟥 Redis This app demonstrates advanced backend practices for scaling real-time synchronization.

🚀 Advanced Backend Practices to Scale Sync in Real-Time Applications

In real-time applications—especially those involving collaborative interfaces or live dashboards—scaling synchronization across multiple clients becomes increasingly challenging. As the user base grows, maintaining consistent state, low latency, and high availability requires more than just basic socket implementations.

✅ Key Topics Covered

• 📡 Efficient Redis Pub/Sub for broadcasting state changes across distributed socket servers
• 🧱 State normalization using Redis key-value structures to reduce payload size
• 🚀 Redis caching with TTL to optimize API performance
• 🔐 Stateless socket authentication for scalable, secure client connections
• 🧭 Horizontal scaling of Socket.IO using adapters like socket.io-redis

⚙️ Use Case Example

Imagine a shared board with 1000 checkboxes 🟩:

• 🔁 State updates are stored & fetched from Redis
• 🔄 Changes broadcasted instantly to all clients
• 🧠 Data consistency is maintained across distributed servers

This architecture ensures:

• 📌 All users are in sync
• 📈 Server instances can scale horizontally
• ⚡ Minimal latency, even with heavy load

🛠️ Tech Stack

Tool	Role
🟩 Node.js	Backend runtime environment
🚀 Express	Server & routing
🌐 Socket.IO	Real-time bi-directional communication
🟥 Redis	In-memory store for Pub/Sub & caching

🧪 Run Locally

🔁 Clone the repository

git clone https://github.com/malhotraarshdeepsingh/RedioSync
cd RedioSync

📦 Install Dependencies

npm install

🐳 Run Redis

docker compose up

⚠️ Note: Make sure your Docker is up and running before executing this command.

▶️ Start the app

npm run dev

➕ To start another instance

🪟 For Windows PowerShell

$env:PORT=8080; npm run dev

💻 On macOS/Linux

PORT=8080 && npm run dev