🧠 CodeVerse — AI-Powered Coding Mentor

Your personal AI tutor that explains code like a patient teacher, not a textbook

🎓 Final Year Project | B.Tech Computer Science & Engineering

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📌 Table of Contents

• Overview
• Live Demo
• Features
• Architecture
• Tech Stack
• How It Works
• API Reference
• Database Schema
• Security
• Local Setup
• Deployment
• Test Results
• Screenshots
• Future Enhancements

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🌟 Overview

CodeVerse is a full-stack AI-powered coding mentor built for absolute beginners. Instead of just answering questions, it teaches — using real-life analogies, code examples, interactive quizzes, and personalized code reviews.

A student types: "What is a variable?"
CodeVerse explains it like a labeled box 📦
Shows a code example 💻
Gives a "Try it yourself" challenge 🎯
Tracks their XP and progress 📊

Built as a Final Year Project demonstrating full-stack development, AI integration, database design, security implementation, and cloud deployment.

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🚀 Live Demo

🔗 https://neuralcode.onrender.com

Credential	Value
Demo mode	Click "Continue as Guest" — no login needed
Register	Create a free account to save progress

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✨ Features

🤖 AI Mentor Chat 4 intelligent chat modes: 🧠 Explain Mode — Plain English with analogies 🐛 Debug Mode — Find and fix bugs step-by-step 🎯 Challenge Mode — Practice tasks with hints 👶 ELI5 Mode — Explain like you're 5 years old	🎯 AI Quiz Generator 6 topic categories (JS, Python, HTML, OOP...) 5 fresh AI-generated questions every session Never the same quiz twice Instant explanations on wrong answers XP rewards for completion
🔍 AI Code Reviewer Score 0–100 with letter grade 3 metrics: Readability, Correctness, Best Practices Colour-coded feedback (✓ good / ⚠ warn / ✕ bad) Optional: Show improved version of code Beginner-friendly explanations	📚 History & Progress Full chat history saved to MongoDB All quiz results with scores and times XP system with 6 levels (Beginner → Pro Coder) Achievements and streak counter Learning roadmap with progress tracking

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🏗 System Architecture

┌─────────────────────────────────────────────────────────┐
│                     CLIENT BROWSER                       │
│              (Single Page App - index.html)              │
│                                                          │
│   ┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────┐  │
│   │  Auth UI │ │Chat Page │ │Quiz Page │ │ History  │  │
│   └────┬─────┘ └────┬─────┘ └────┬─────┘ └────┬─────┘  │
│        └────────────┴────────────┴────────────┘         │
│                          │ HTTPS                         │
└──────────────────────────┼──────────────────────────────┘
                           │
                           ▼
┌─────────────────────────────────────────────────────────┐
│                  EXPRESS.JS BACKEND                      │
│              (Node.js — Render.com)                      │
│                                                          │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────────┐  │
│  │ Auth Routes │  │  AI Routes  │  │ History Routes  │  │
│  │ /auth/login │  │  /api/chat  │  │/api/history/... │  │
│  │ /auth/reg.. │  │  /api/quiz  │  │                 │  │
│  └──────┬──────┘  └──────┬──────┘  └────────┬────────┘  │
│         │                │                  │            │
└─────────┼────────────────┼──────────────────┼───────────┘
          │                │                  │
          ▼                ▼                  ▼
┌─────────────────┐  ┌──────────────────┐  ┌──────────────────┐
│  MongoDB Atlas  │  │ Google Gemini    │  │  MongoDB Atlas   │
│  (User Accounts │  │ API              │  │  (Chat History   │
│   XP, Progress) │  │ (gemini-1.5-mini)│  │   Quiz Results)  │
└─────────────────┘  └──────────────────┘  └──────────────────┘

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🔄 How It Works

User Authentication Flow

User submits form
       │
       ▼
  Input validation
  (email regex, pw length)
       │
       ▼
  bcrypt.hash(password, 12)
       │
       ▼
  Save to MongoDB
       │
       ▼
  jwt.sign({ id, email }) ──► Returns JWT token
       │
       ▼
  Frontend stores token
  in localStorage
       │
       ▼
  Every API request sends:
  Authorization: Bearer <token>

AI Chat Flow

User sends message
       │
       ▼
  authRequired middleware
  verifies JWT token
       │
       ├── Invalid → 401 Unauthorized
       │
       ▼ Valid
  POST to Google Gemini API
  (gemini-1.5-mini-latest)
  with system prompt + message
       │
       ▼
  AI response received
       │
       ├──► Send reply to frontend
       │
       └──► Save to MongoDB
            (chat history)

Quiz Generation Flow

User picks topic
       │
       ▼
  Backend sends prompt to Gemini API:
  "Generate 5 MCQ questions about [topic]
   Return ONLY JSON array"
       │
       ▼
  safeParseJSON() extracts
  clean JSON from response
       │
       ▼
  5 questions rendered
  with A/B/C/D options
       │
       ▼
  User answers → score calculated
  → XP awarded → result saved
  to MongoDB quiz history

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🛠 Tech Stack

Layer	Technology	Purpose
Frontend	HTML5 + CSS3 + Vanilla JS	Single page app, no framework
Backend	Node.js + Express.js	REST API server
Database	MongoDB Atlas + Mongoose	User data, chat/quiz history
AI Engine	Google Gemini API (gemini-1.5-mini-latest)	Chat, quiz generation, code review
Auth	JWT + bcryptjs	Secure authentication
Hosting	Render.com	Free Node.js hosting
Version Control	GitHub	Source code management

Why these choices?

Decision	Reason
Vanilla JS (no React)	Simpler for FYP, shows core JS understanding
Gemini for AI tasks	Free tier with generous limits, multimodal capabilities, reliable API
MongoDB over SQL	Flexible schema for evolving user data, free Atlas tier
Render over Vercel	Vercel doesn't support Express app.listen(), Render does
bcrypt cost 12	Balance between security and performance

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📊 API Reference

Authentication Routes

Method	Endpoint	Auth	Description
POST	/auth/register	❌	Register new user
POST	/auth/login	❌	Login, returns JWT
GET	/auth/me	✅ JWT	Get current user

AI Routes (all require JWT)

Method	Endpoint	Body	Description
POST	/api/chat	{systemPrompt, userMessage}	AI mentor response
POST	/api/quiz	{topic}	Generate 5 quiz questions
POST	/api/review	{code, lang, beginner, rewrite}	Code review

Progress Routes

Method	Endpoint	Auth	Description
PATCH	/user/progress	✅ JWT	Save XP, stats, progress

History Routes (all require JWT)

Method	Endpoint	Description
POST	/api/history/chat	Save chat message pair
GET	/api/history/chats	List all chat sessions
GET	/api/history/chat/:id	Get full conversation
DELETE	/api/history/chat/:id	Delete chat
POST	/api/history/quiz	Save quiz result
GET	/api/history/quizzes	List all quiz attempts

Example Response — /api/quiz

{
  "questions": [
    {
      "q": "What is a variable in JavaScript?",
      "options": [
        "A) A fixed value that never changes",
        "B) A named container that stores a value",
        "C) A type of function",
        "D) A loop structure"
      ],
      "correct": 1,
      "explain": "A variable is like a labeled box — you give it a name and store something inside it."
    }
  ]
}

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🗄 Database Schema

Users Collection

{
  _id: ObjectId,
  name:      String,        // "Swati Chaudhary"
  email:     String,        // unique, lowercase
  password:  String,        // bcrypt hash "$2a$12$..."
  role:      String,        // "student" | "self" | "career" | "other"
  xp:        Number,        // 0–∞ experience points
  streak:    Number,        // days in a row active
  stats:     [Number],      // [questions, quizzes, reviews, 0]
  progress:  [Number],      // [html%, js%, python%, algo%]
  createdAt: Date
}

Chats Collection

{
  _id:      ObjectId,
  userId:   ObjectId,       // ref: User
  mode:     String,         // "explain" | "debug" | "challenge" | "eli5"
  title:    String,         // first 40 chars of first message
  messages: [{
    role:    String,        // "user" | "ai"
    content: String,
    time:    Date
  }],
  createdAt: Date,
  updatedAt: Date
}

Quizzes Collection

{
  _id:       ObjectId,
  userId:    ObjectId,      // ref: User
  topic:     String,        // "JavaScript fundamentals..."
  score:     Number,        // correct answers
  total:     Number,        // total questions (5)
  timeTaken: Number,        // seconds
  questions: Array,         // full question data
  createdAt: Date
}

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🔐 Security

Feature	Implementation	Why
Password hashing	bcrypt.hash(pw, 12)	Bcrypt is slow by design — resistant to brute force
JWT authentication	jwt.sign({id}, SECRET, {expiresIn: '7d'})	Stateless, no server-side sessions needed
Input validation	Custom validateFields() + regex	Prevents NoSQL injection, XSS
Protected routes	authRequired middleware	Every AI/history route requires valid JWT
API key security	Server-side only via process.env	Key never reaches browser
CORS	cors({origin: true})	Safe — JWT is the actual auth layer
Request limits	express.json({limit: '50kb'})	Prevents payload attacks
Timing attack prevention	Always calls bcrypt.compare() even if user not found	Constant-time response

Security Test Results

✅ Unauthenticated API request    → 401 "No token provided"
✅ Fake JWT token                 → 401 "Invalid token"
✅ Expired JWT token              → 401 "Session expired"
✅ Wrong password                 → 401 "Invalid email or password"
✅ Duplicate email                → 409 "Account already exists"
✅ NoSQL injection attempt        → 400 "Invalid email format"
✅ Password in database           → "$2a$12$..." (bcrypt hash)
✅ API key in browser             → Not found (server-side only)

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🚀 Local Setup

Prerequisites

• Node.js v18+
• MongoDB Atlas account (free)
• Groq API key (free)

Step 1 — Clone

git clone https://github.com/ChaudhariSwati/CodeVerse.git
cd CodeVerse

Step 2 — Install dependencies

npm install

Step 3 — Create .env file

GROQ_API_KEY=your_groq_key_here
MONGO_URI=mongodb+srv://username:password@cluster.mongodb.net/neuralcode?retryWrites=true&w=majority
JWT_SECRET=any_long_random_string_here_min_32_chars
PORT=3001

Step 4 — Run

node server.js

Step 5 — Open

http://localhost:3001

You should see:

✅ MongoDB connected
🚀 CodeVerse server running on http://localhost:3001
🤖 AI engine: Groq (llama-3.3-70b-versatile)

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☁️ Deployment

Deployed on Render.com (free tier).

GitHub Push → Render detects change → npm install → node server.js → Live

Render Configuration

Setting	Value
Build Command	npm install
Start Command	node server.js
Environment	Node
Auto-Deploy	Yes (on every git push)

Environment Variables on Render

GROQ_API_KEY   = gsk_...
MONGO_URI      = mongodb+srv://...
JWT_SECRET     = ...

⚠️ MongoDB Atlas: Set Network Access to 0.0.0.0/0 (allow all IPs) so Render's servers can connect.

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🧪 Test Results

Functional Tests

#	Test Case	Expected	Result
T01	Register with valid details	Account created, JWT returned	✅ Pass
T02	Register with duplicate email	409 error shown	✅ Pass
T03	Login with correct credentials	Dashboard opens	✅ Pass
T04	Login with wrong password	Error message shown	✅ Pass
T05	Auto-login on page refresh	Dashboard loads without login	✅ Pass
T06	AI chat responds	Answer displayed	✅ Pass
T07	Quiz generates 5 questions	Questions appear with options	✅ Pass
T08	Code review returns score	Score 0-100 with feedback	✅ Pass
T09	XP saves to MongoDB	XP persists after logout/login	✅ Pass
T10	Chat history saved	Previous chats appear in History	✅ Pass

Security Tests

#	Test Case	Expected	Result
S01	Call /api/chat without token	401 Unauthorized	✅ Pass
S02	Call /api/chat with fake token	401 Invalid token	✅ Pass
S03	Password field in MongoDB	bcrypt hash visible	✅ Pass
S04	NoSQL injection in email field	400 Invalid format	✅ Pass
S05	Groq API key in browser console	Not found	✅ Pass

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🔮 Future Enhancements

Feature	Priority	Description
Streaming AI responses	🔴 High	Word-by-word like ChatGPT using SSE
Code execution	🔴 High	Run code in browser via Judge0 API
PWA / Mobile app	🟡 Medium	Installable on phone via manifest.json
Dark mode	🟡 Medium	CSS variable toggle
Daily streak emails	🟡 Medium	Nodemailer reminders
Leaderboard	🟢 Low	Top XP earners this week
Multi-language	🟢 Low	Hindi, Marathi UI support

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📄 Project Documentation

Document	Description
CodeVerse_SRS.docx	Software Requirements Specification — functional & non-functional requirements, use cases
CodeVerse_Project_Report.docx	Full 8-chapter academic report — literature review, design, implementation, testing
CodeVerse_Test_Plan.docx	53 test cases with expected and actual results

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👩‍💻 Author

Swati Chaudhary Final Year B.Tech — Computer Science & Engineering

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📝 License

MIT License — free to use, modify and distribute

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