NQTCoder - Elite MERN Recruitment Practice Arena

🌐 Live Deployments

• Frontend Application (Vercel): https://nqtcoder.vercel.app
• Backend REST API (Render): https://nqtcoder.onrender.com

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NQTCoder is a production-ready, full-stack MERN coding assessment platform modeled after technical recruitment and competitive programming environments used by global enterprise recruiters (such as TCS NQT, Accenture, Wipro, Cognizant, etc.).

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🚀 Core Architectural Features

• Assessment UI (Split-Screen Arena): A modern split-screen coding interface. The left panel houses the problem statement, parameters, examples, and constraints; the right panel incorporates the code editor and terminal.
• Monaco Editor Integration: Embedded with professional syntax highlighting for C++, Java 8, and Python 3. Supports standard libraries and full boilerplate structure imports.
• Security-First Test Case Architecture: Test cases are partitioned into visible and hidden types. Hidden test cases are completely stripped from client payloads and only verified securely on the server-side compiler.
• Robust Sandbox Code Execution: Supports dual compilation modes:
  • Local Compiler Pipeline: Executes code securely on the local operating system (ideal for development).
  • Judge0 Sandbox Integration: Leverages API-based remote compilers for safe execution in isolated sandbox environments.
• Countdown Assessment Timer: Exam-grade ticking countdown timer that automatically locks the editor and submits code upon expiration.
• Dynamic Leaderboard & Solver Profiles: Real-time global student solver ranking based on solving statistics (Easy, Medium, Hard breakdown) with page pagination.
• Admin Dashboard: Administrative interface to add, modify, or retire coding challenges, upload test cases, and review user analytics.
• Google OAuth 2.0 Integration: Direct one-click login and registration using Google Client authentication.

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🛠️ Technology Stack

• Frontend: React, Tailwind CSS, Vite, Monaco Editor, React Router DOM, Axios.
• Backend: Node.js, Express.js, JSON Web Tokens (JWT), bcrypt.
• Database: MongoDB Atlas (Mongoose ODM).

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📦 Directory Structure

NQTCoder/
├── backend/            # Express REST API & Code Compilation Suite
│   ├── config/         # Database and Seeder scripts
│   ├── controllers/    # Route controllers (Auth, Questions, Submissions)
│   ├── middleware/     # JWT Auth, admin boundaries, error handlers
│   ├── models/         # Database Schemas (User, Question, Submission)
│   ├── routes/         # Express API endpoints
│   ├── utils/          # Local runner and Judge0 sandbox integrations
│   └── server.js       # Main server entrypoint
└── frontend/           # React Single Page Application (SPA) client
    ├── src/
    │   ├── components/ # Shared UI components (Monaco Editor, Timer, Console)
    │   ├── context/    # Global Authentication State
    │   ├── pages/      # Dashboards, Practice Arena, Leaderboard, Profiles
    │   └── services/   # Axios HTTP request services
    └── vite.config.js  # Vite dev server and proxy config

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⚙️ Environment Variables Setup

Configure the following variables to authenticate and boot the platform.

Backend Config (backend/.env)

PORT=5000
MONGO_URI=your_mongodb_connection_string
JWT_SECRET=your_secure_jwt_token_secret

# OAuth Configurations
GOOGLE_CLIENT_ID=your_google_oauth_client_id
CLIENT_URL=http://localhost:5173

# Admin Setup (Will seed on first database connection)
ADMIN_EMAIL=your_desired_admin_email@domain.com
ADMIN_PASSWORD=your_desired_strong_admin_password

# Email SMTP Setup (For local verification OTPs)
EMAIL_USER=your_smtp_email@gmail.com
EMAIL_PASS=your_smtp_app_password

# Brevo Setup (Preferred in production to bypass Render outgoing SMTP blocks)
BREVO_API_KEY=your_brevo_api_key

# Compilation Mode ('local' or 'judge0')
RUN_MODE=local

# Local Java 8 Executable Path (Optional, if not in system PATH)
# JAVA_8_BIN=C:\Program Files\Java\jdk-1.8\bin

Frontend Config (frontend/.env)

VITE_GOOGLE_CLIENT_ID=your_google_oauth_client_id

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⚡ Local Development & Setup

Follow these steps to run the platform locally on your computer:

1. Start the Backend API

1. Navigate to the backend directory:

   cd backend

2. Install dependencies:

   npm install

3. Boot the development server:

   npm run dev

   Note: On first startup, if ADMIN_EMAIL and ADMIN_PASSWORD are configured in .env, the server will seed the initial Admin account and challenges.

2. Start the Frontend Dev Server

1. Navigate to the frontend directory:

   cd ../frontend

2. Install dependencies:

   npm install

3. Boot the development server:

   npm run dev

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🌐 Production Deployment Guide

To deploy this application for real-world production users:

1. Database (MongoDB Atlas)

1. Register a cluster on MongoDB Atlas.
2. Set up database access credentials and allow IP access (0.0.0.0/0 for deployment).
3. Copy the database connection string and use it as MONGO_URI in the backend environment.

2. Backend API (Render / Heroku)

1. Deploy the backend/ subfolder.
2. In the deployment settings, configure the build command as npm install and start command as node server.js (or npm start).
3. Add all environment variables from backend/.env in the deployment settings dashboard.

3. Frontend UI (Vercel / Netlify / Render)

1. Deploy the frontend/ subfolder.
2. Configure the build command as npm run build and publish directory as dist/.
3. Set the VITE_GOOGLE_CLIENT_ID in the deployment settings.

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👥 Contributors

• Veerendra Kumar (@kumar-veerendra) — System Architecture, Compiler Pipeline, & Backend Engineering.
• Satyam Kumar (@vishen-satyamkumar) — Frontend Engineering, Monaco Editor Integration & Interface Design.

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📄 License

This project is licensed under the MIT License. See the LICENSE file for details.