Built a Scalable Online Coding Platform (Turborepo + AWS + Load Balancing + Judge0)

I recently built a high-performance online coding platform designed to handle large user traffic — from code execution to problem uploads and real-time output.

 

⚙️ Tech Stack & Architecture :

 

⚈ Turborepo monorepo

⚈ Node.js Backend + React Frontend

⚈ AWS EC2 for Judge0 execution layer

⚈ AWS Load Balancer to distribute execution load

⚈ NeonDB (PostgreSQL) for scalable storage

⚈ Redis Queue + Redis Pub/Sub for job distribution & real-time events

⚈ Workers for parallel code execution

⚈ WebSockets for instant output delivery

⚈ Admin Panel to upload and manage coding problems

 

🔄 How It Works (Short Flow) :

 

1. User submits code

2. Backend stores metadata in NeonDB

3. Job enters Redis Queue

4. Multiple Workers pick tasks

5. Workers send execution requests to AWS Load Balancer → Judge0 servers

6. Judge0 returns stdout/stderr

7. Worker saves result in NeonDB

8. Worker triggers Redis Pub/Sub event

9. Backend sends output to user through WebSockets

 

📌 Built for Scale :

 

⚈ Horizontal scaling with multiple Workers

⚈ Load-balanced Judge0 servers

⚈ Event-driven architecture

⚈ Admin can upload/manage problems dynamically