ChampKoder
ProductPortfolio Highlight
Built and maintained an interactive programming LMS serving 200+ daily users, combining conventional LMS functionality with online code execution and automated programming evaluation.
Overview
ChampKoder is an interview preparation platform at champkoder.com where developers master coding interviews through structured roadmaps, coding problems, quizzes, interview Q&A, CV building, and ATS resume checking. The platform combines traditional LMS functionality with Judge0-powered code execution so learners practice, submit solutions, and receive immediate feedback.
Problem
Traditional LMS platforms are mainly designed around videos, documents, courses, and quizzes. Programming education and interview prep require students to actually write and execute code, compete on leaderboards, and prepare tailored resumes — not just watch lessons.
Solution
Built an all-in-one interview prep platform with courses, roadmaps, problem sets with test-case evaluation, live quizzes, CV builder with PDF export, ATS resume checker, and a gamified leaderboard. Judge0 handles secure code execution while Redis and RabbitMQ keep submissions and caching fast under concurrent student load.
Core Features
Structured roadmaps
Daily learning plans that guide developers through interview prep step by step.
Coding problem sets
Curated challenges with difficulty levels, rewards, and unlockable tutorials after submission.
Quiz system
Interview-style quizzes with automatic evaluation, scores, and progress tracking.
Online code execution
Judge0 integration lets users run programming solutions against test cases without local setup.
CV builder
Software engineer CV builder with multiple templates, live preview, and PDF download.
ATS resume checker
Upload a resume and job description to get ATS score, keyword match, and AI-powered tips.
Leaderboard
Gamified ranking system with diamonds and coins to motivate consistent practice.
Interview Q&A
Subject-wise interview preparation content alongside courses and practice problems.
Screenshots
Major Challenges
Secure code execution
Running arbitrary user-submitted code is a major security concern. The execution environment must be isolated from the main application via Judge0.
Handling concurrent submissions
When many students submit code simultaneously, the application must not become blocked. Asynchronous processing and queues keep the system responsive.
Performance
The platform handles course browsing, quiz attempts, code submissions, and result retrieval without slowing down the user experience.
Learning progress tracking
Tracking where each student is in their journey requires careful modeling of courses, lessons, quizzes, and submissions.
My Role
- Designed backend architecture and REST APIs
- Implemented LMS functionality and course progression
- Built quiz system with automatic evaluation
- Implemented programming challenge and submission system
- Integrated Judge0 for secure code execution
- Built CV builder and ATS resume checker features
- Implemented Redis caching for performance
- Implemented RabbitMQ-based asynchronous processing
- Designed database models for courses, quizzes, and submissions
- Optimized backend performance and deployment infrastructure
What I Learned
- Isolated code execution (Judge0) is non-negotiable — never run student code in your application process.
- Queue-based submission handling scales better than synchronous execution when class sizes grow.
- Combining LMS, competitive programming, and career tools in one platform requires clear navigation and shared progress models.
- Caching course content and quiz metadata with Redis materially improves browse performance at 200+ daily users.
Tech Stack
- Python
- Django
- DRF
- MySQL
- PostgreSQL
- Redis
- RabbitMQ
- Judge0
- React
- Linux
- Docker
- Git
Explore this project
View the live demo or browse the source code on GitHub.