Codeforces

A full-stack competitive programming platform inspired by Codeforces. Built to learn and understand remote code execution in a fast, secure, and reliable way using micro VMs and sandboxed environments.

Tech Stack

Layer	Technology
Frontend	Next.js 16, React 19, Tailwind CSS
Code Editor	Monaco Editor with multi-language support
Backend	Express 5, TypeScript
Database	PostgreSQL with Prisma ORM
Auth	Better-auth (email/password + email OTP)
Code Execution	Judge0 (self-hosted or managed)
Monorepo	Turborepo + pnpm
Optional	Redis (queue), Firecracker / E2B (micro VMs)

Features

• Code Arena — Split-pane IDE with problem description, Monaco editor, and test case panels
• Multi-language support — C++, Python, Java, JavaScript, TypeScript, Go, Rust
• Problem management — Admin panel for creating problems with visible/hidden test cases and starter code
• Run & Submit — Test against sample cases instantly or submit against all hidden test cases
• Cursor pagination — Efficient browsing of the problem set
• Submission verdicts — AC, WA, TLE, MLE, RE, CE
• Progress tracking — See solved, attempted, and unsolved problems at a glance
• Email OTP verification — Powered by Resend + React Email

Project Structure

apps/
  web/         → Next.js frontend
  backend/     → Express API server
  worker/      → Background job runner (Redis-based)
packages/
  database/    → Prisma schema & client
  email/       → Email templates & service
  ui/          → Shared UI components
  common/      → Shared types, schemas, constants

Code Execution Options

1. Judge0 (easiest) — Send code to a self-hosted or public Judge0 API
2. E2B (medium) — Run code in managed or self-hosted sandboxes
3. Firecracker (hard) — Spin up micro VMs natively on a worker

Getting Started

# Install dependencies
pnpm install

# Set up environment variables
cp apps/backend/.env.example apps/backend/.env
cp apps/web/.env.example apps/web/.env

# Push database schema
pnpm --filter database db:push

# Run the dev servers
pnpm dev

API Routes

• POST /api/auth/* — Authentication (sign-up, sign-in, OTP)
• GET /api/user/problems — Browse problems with cursor pagination
• POST /api/judge0 — Execute code & check submissions
• CRUD /api/admin/problems — Admin problem management
• GET /api/tags — List all problem tags