Atlas: Open-Source CTF Platform

The Problem

Running a Capture The Flag (CTF) competition requires a robust platform that can handle real-time scoring, team management, and concurrent users—all while maintaining security and fairness.

The goal: Build an open-source CTF platform capable of handling large-scale competitions.

Technical Implementation

Architecture

Built a full-stack platform with a Django backend and React frontend:

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  React Frontend │────▶│  Django Backend │────▶│   PostgreSQL    │
│  (Competition   │     │  (API + Auth +  │     │  (Challenges +  │
│   Dashboard)    │     │   Scoring)      │     │   Submissions)  │
└─────────────────┘     └─────────────────┘     └─────────────────┘

Key Technical Implementations

Feature	Implementation	Result
Real-time Scoring	WebSocket + Django Channels	Live leaderboard updates
User Authentication	Django Auth + JWT	Secure team-based access
Team Management	Custom Django models	Flexible team creation/joining
Deployment	Docker containerization	Stable, reproducible deployment
Database	PostgreSQL	ACID compliance for scoring integrity

Production Results: Web Club CTF 2025

Successfully deployed and operated during Web Club CTF 2025:

• 250+ participants actively competing
• 100+ teams registered and playing
• Zero downtime throughout the competition
• Real-time scoring with sub-second leaderboard updates

Tech Stack Rationale

Why Django?

• Robust ORM for complex challenge/submission relationships
• Built-in admin for challenge management
• Excellent security defaults for a competition platform

Why Docker?

• Consistent environment across development and production
• Easy horizontal scaling if needed
• Simplified deployment for other CTF organizers

What I Learned

What Worked Well

1. Django’s ORM: Made complex queries for scoring and leaderboards straightforward.

2. Docker containerization: Deployment was smooth and reproducible.

3. Real-time architecture: WebSocket integration provided excellent user experience.

Future Plans

1. Add challenge isolation: Sandboxed execution for dynamic challenges.

2. Improve scalability: Add Redis caching for leaderboard queries.

3. Enhance analytics: Post-competition statistics and insights.

Open Source

Atlas is maintained as an open-source project under the Web Enthusiasts’ Club at NITK.

• GitHub Repository