{CodeSniff}

AI-Based Code Plagiarism Detector

Detect code similarity instantly using K-gram tokenization and Winnowing algorithm

🌐 Live Demo · 📝 Report Bug · ✨ Request Feature

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About

"In a world where code is copied, CodeSniff sees what eyes can't."

CodeSniff is a token-based code similarity analyzer designed to detect plagiarism in Java source files. It uses the K-gram fingerprinting technique combined with the Winnowing algorithm — the same approach used by Stanford's MOSS system — to identify copied code even when variable names are changed, comments are removed, or statements are reordered.

Currently supporting Java with plans to expand to Python, C++, JavaScript and more in future releases through AI-powered semantic analysis.

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🚀 Features

⚠️ Current Version (v0.5): Supports Java source files only. Multi-language support planned for v2.5.

• 🔍 Token-based similarity detection using K-gram algorithm
• 🪟 Winnowing algorithm for efficient fingerprint selection
• ☕ Java source file upload and pairwise comparison
• 💻 Direct code paste for quick Java code analysis
• 📊 Similarity percentage results table
• 📥 CSV report download
• ⚙️ Configurable options — K-gram size, window size, ignore comments
• 🌐 Fully deployed on cloud infrastructure

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🛠️ Tech Stack

Frontend

Technology	Purpose
HTML5 / CSS3	UI structure and styling
Vanilla JavaScript	SPA routing and API calls
Vercel	Hosting and deployment

Backend

Technology	Purpose
Java 17	Core language
Spring Boot 3.3.5	REST API framework
Maven	Build and dependency management
Azure App Service F1	Cloud hosting (24/7)

Database & Infrastructure

Technology	Purpose
PostgreSQL (Supabase)	Database
GitHub Actions	CI/CD pipeline
Nginx	Reverse proxy

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🏗️ System Architecture

User Browser
     │
     ▼
┌─────────────────┐
│  Vercel          │  codesniff.tech
│  (Frontend)      │  HTML + CSS + JS
└────────┬────────┘
         │ API calls
         ▼
┌─────────────────────────┐
│  Azure App Service F1    │  codesniff-backend.azurewebsites.net
│  Spring Boot Backend     │
│  ┌─────────────────┐    │
│  │AnalyzeController│    │
│  └────────┬────────┘    │
│           │              │
│  ┌────────▼────────┐    │
│  │SimilarityEngine  │    │
│  └────────┬────────┘    │
│           │              │
│  ┌────────▼────────┐    │
│  │Tokenizer         │    │
│  └────────┬────────┘    │
│           │              │
│  ┌────────▼────────┐    │
│  │CodeNormalizer    │    │
│  └─────────────────┘    │
└───────────┬─────────────┘
            │
            ▼
┌─────────────────┐
│  Supabase        │  PostgreSQL Database
│  (Database)      │
└─────────────────┘

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🔬 Detection Pipeline

Input Code
    │
    ▼
1. Code Normalization    → Remove comments, whitespace, lowercase
    │
    ▼
2. Tokenization         → Convert code to token stream
    │
    ▼
3. K-gram Generation    → Create overlapping k-grams (default k=6)
    │
    ▼
4. Hashing              → Hash each k-gram
    │
    ▼
5. Winnowing            → Select minimum hashes per window
    │
    ▼
6. Fingerprint Compare  → Jaccard similarity between fingerprint sets
    │
    ▼
Similarity Score (0% - 100%)

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📦 Clone Types Detected

Clone Type	Description	Detected
Type 1	Exact copy	✅
Type 2	Renamed identifiers	✅
Type 3	Added/removed statements	✅
Type 4	Semantic similarity	⚠️ Partial

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🚀 Getting Started

Prerequisites

• Java 17+
• Maven 3.9+
• PostgreSQL (or Supabase account)

Installation

# Clone the repository
git clone https://github.com/Kunal-htr/codesniff.git

# Navigate to project
cd codesniff

# Install dependencies
mvn clean install

Configuration

Create src/main/resources/application.properties:

server.port=9090
spring.datasource.url=jdbc:postgresql://your-db-host:5432/postgres
spring.datasource.username=your-username
spring.datasource.password=your-password
spring.datasource.driver-class-name=org.postgresql.Driver
spring.jpa.hibernate.ddl-auto=update

Run Locally

mvn spring-boot:run

Open http://localhost:9090 in your browser.

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🔌 API Reference

Analyze Code Similarity

POST /api/analyze
Content-Type: application/json

Request Body:

{
  "submissions": [
    { "name": "A.java", "content": "public class A { ... }" },
    { "name": "B.java", "content": "public class B { ... }" }
  ],
  "options": {
    "omitComments": true,
    "k": 6,
    "window": 4
  }
}

Response:

{
  "summary": [
    {
      "a": "A.java",
      "b": "B.java",
      "score": 0.451
    }
  ]
}

Health Check

GET /api/health

CodeSniff is alive!

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📁 Project Structure

codesniff/
├── src/
│   └── main/
│       ├── java/
│       │   └── backend/
│       │       ├── App.java                 # Spring Boot entry point
│       │       ├── AnalyzeController.java   # REST API endpoints
│       │       ├── SimilarityEngine.java    # Core detection logic
│       │       ├── Tokenizer.java           # Code tokenization
│       │       ├── CodeNormalizer.java      # Code preprocessing
│       │       └── CorsConfig.java          # CORS configuration
│       └── resources/
│           └── static/
│               ├── index.html               # Frontend UI
│               ├── app.js                   # Frontend logic
│               └── style.css                # Styling
├── frontend/                                # Vercel deployment
├── .github/workflows/                       # CI/CD pipeline
├── Dockerfile                               # Container config
└── pom.xml                                  # Maven config

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🔄 CI/CD Pipeline

git push to main
      │
      ▼
GitHub Actions triggers
      │
      ▼
Maven build + test
      │
      ▼
Deploy to Azure App Service
      │
      ▼
Live in ~50 seconds ✅

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📊 Performance

Metric	Value
Average response time	~200ms
Max file size	1MB
Supported languages	All text-based
Concurrent comparisons	Multiple pairs

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📦 Modules

Module	Name	Status	Version
Module 1	Similarity Engine	✅ Complete	v0.5
Module 2	UI & User Workflow	🔄 Planned	v1.0
Module 3	Report Visualization	🔄 Planned	v1.5
Module 4	Database & Storage	🔄 Planned	v2.0
Module 5	Future AI Enhancements	🔄 Planned	v2.5

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📄 License

This project is licensed under the MIT License.

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🙏 Acknowledgements

• Spring Boot
• Supabase
• Vercel
• Azure
• Winnowing Algorithm — Schleimer, Wilkerson, Aiken (2003)

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Made with ❤️ by Kunal Patel

⭐ Star this repo if you found it helpful!