⌁ JudgeX

An AI-assisted online judge — write code in the browser, run it in a sandbox, get an instant verdict and an AI review.

 

$ judgex submit two-sum.cpp --lang cpp
→ queued · compiling in gcc:14 sandbox…
→ running testcases  [▇▇] 2/2
» AC  accepted · 2/2 · 871ms · 5.2mb
→ ai review · O(n) · hashing

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✦ Features

• 5 languages — C, C++, Java, Python, JavaScript, each run in its own image.
• Sandboxed judging — every submission compiles and runs in an isolated Docker container (memory-capped, 1 CPU, no network).
• Real verdicts — AC · WA · TLE · RE · CE, measured on hidden test cases with execution time & memory.
• AI code review — Google Gemini reads your accepted solution and returns a summary, complexity, and optimization hints.
• Live results — verdicts update in place, Codeforces-style, while the judge works.
• The rest — JWT auth, problem set (Easy → Hard), global leaderboard, profiles, submission history, and Swagger API docs.

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✦ Architecture

A three-service design glued by a Redis queue — the code executor is fully decoupled from the API so untrusted code stays isolated and can scale on its own.

flowchart LR
    U([Browser]) --> N[Nginx]
    N --> F[React SPA]
    N -->|/api| B[Express API]

    B -->|submissionQueue| R[(Redis + BullMQ)]
    R --> C[Compiler Service]
    C -->|dockerode| D[[Docker Sandbox]]
    C -->|verdict| M[(MongoDB Atlas)]
    C -->|ai-analysis| R
    R --> B
    B -->|review| G([Gemini AI])
    B <--> M

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judgex/
├── frontend/   →  React + Vite SPA (Tailwind, Monaco editor)
├── backend/    →  Express API + JWT auth + AI worker
├── compiler/   →  the judge — sandboxed Docker execution (5 languages)
└── docker-compose.yml

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✦ Tech Stack

Layer	Stack
Frontend	React 19 · Vite · Tailwind CSS v4 · Monaco Editor · React Query
Backend	Node.js · Express · Mongoose · JWT · Swagger
Compiler	Node.js · dockerode · Docker
Queue	Redis · BullMQ
Database	MongoDB Atlas
AI	Google Gemini

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✦ Run it locally

The whole stack runs with one command via Docker Compose.

git clone https://github.com/Sanjeev-07-psypher/Online-Judge.git
cd Online-Judge

# 1. create the env files (see below)
# 2. pull the language images the judge uses
docker pull gcc:14 python:3.12-slim node:20-slim eclipse-temurin:21-jdk

# 3. build & start everything
docker compose up -d --build

Open http://localhost — Swagger at /api-docs, queue dashboard at /admin/queues.

Environment variables

# backend/.env
MONGO_URI=          # MongoDB Atlas connection string
JWT_SECRET=         # any long random string
GEMINI_API_KEY=     # Google Gemini API key

# compiler/.env
MONGO_URI=          # same connection string

REDIS_HOST, REDIS_PORT and PORT are provided by Compose — no need to set them.

Prefer running without Docker?

Requires Node 20+, a running Redis, and Docker (for the judge). In three terminals:

cd backend  && npm install && npm run dev      # API  :5000
cd compiler && npm install && npm run dev      # judge worker
cd frontend && npm install && npm run dev      # UI   :5173

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✦ Roadmap

• AI coding coach — progressive hints & mock interviews
• Live contests + Codeforces-style rating
• Company Prep — curated, role-based problem tracks
• More languages (Go, Rust)

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Built with ☕ and a terminal  ·  judgex.online