Quick Start

Backend

cd backend
npm install

Create .env:

NODE_ENV=development
PORT=5000
MONGODB_URI=<your_mongodb_uri>
FRONTEND_URL=http://localhost:5173
# Firebase Admin
FIREBASE_SERVICE_ACCOUNT_PATH=./auth-f9e85-firebase-adminsdk-fbsvc-b06f1890b0.json
# Or set FIREBASE_SERVICE_ACCOUNT_JSON to the service account JSON string
# Judge0 (leave key blank to use public CE)
JUDGE0_BASE=https://ce.judge0.com
# If using RapidAPI:
# JUDGE0_BASE=https://judge0-ce.p.rapidapi.com
# JUDGE0_KEY=<your_rapidapi_key>

Run:

npm run dev

Backend: http://localhost:5000

Frontend

cd frontend
npm install
npm run dev

Frontend: http://localhost:5173

Create frontend/.env:

VITE_API_URL=http://localhost:5000/api
VITE_FIREBASE_API_KEY=<your_firebase_api_key>
VITE_FIREBASE_AUTH_DOMAIN=<your_firebase_auth_domain>
VITE_FIREBASE_PROJECT_ID=<your_firebase_project_id>
VITE_FIREBASE_STORAGE_BUCKET=<your_firebase_storage_bucket>
VITE_FIREBASE_MESSAGING_SENDER_ID=<your_firebase_sender_id>
VITE_FIREBASE_APP_ID=<your_firebase_app_id>

Open the app, sign in with Google, pick a problem, write code, Run (example tests) or Submit (stores result + code in Mongo).

Judge0 Notes

• Without JUDGE0_KEY it uses the public CE endpoint (rate limits apply).
• With JUDGE0_KEY + RapidAPI base it uses authenticated quota.
• Only Python & Java currently mapped (extend LANGUAGE_MAP to add more).

Folder Snapshot

backend/src
  controllers/ (auth, problems, submissions)
  middleware/auth.ts
  models/ (User, Submission)
  utils/fsProblems.ts
frontend/src
  pages/ (Problems, Problem)
  components/

Adding a Problem (for contributors)

1. Create a new folder or file in the backend problems directory following existing slug conventions.
2. Provide metadata (title, difficulty, category, order, examples, etc.) in the same structure as existing problems.
3. Restart the backend; it rescans problems on startup.
4. Verify it appears in the Problems list and examples run via “Run”.
5. Submit a PR including the new problem file only (no .env, no build artifacts).

Environment Security

Never commit real .env values (already ignored by .gitignore).

License

MIT (add a LICENSE file if distributing).