Smart Contract Security Scanner - Starter Template

🚀 AI-powered starter template for building advanced Solidity analysis tools with Claude Sonnet 4

A production-ready starter template for building smart contract analysis tools powered by Claude AI. This project provides a solid foundation for developers who want to create their own customized security scanners, audit tools, or educational platforms for Solidity development.

🎯 What is This?

This is a starter template - think of it as your foundation to build something bigger:

✅ Ready-to-use: Works out of the box with basic vulnerability detection
🛠️ Fully customizable: Modify prompts, add features, integrate with your tools
📚 Learning resource: Understand how AI-powered code analysis works
🚀 Production-ready: Built with Next.js 15, TypeScript, and modern best practices
🎨 Beautiful UI: Glassmorphic design you can adapt to your brand

💡 What Can You Build?

Fork this template and create:

Advanced Audit Platforms: Add multi-contract analysis, dependency scanning, or custom vulnerability detection
Educational Tools: Build interactive learning platforms for smart contract security
CI/CD Integration: Create GitHub Actions or GitLab CI plugins for automated security checks
Specialized Scanners: Focus on specific protocols (DeFi, NFTs, DAOs) with custom detection rules
Team Audit Tools: Add collaboration features, report generation, or integration with project management tools
Custom Reporting: Generate PDF reports, integrate with Notion, or send Slack notifications
Multi-Chain Support: Extend to analyze contracts on different EVM chains with chain-specific checks

🏠 Self-Hosted & Open Source

This is a self-hosted application - you have complete control:

🔒 Full privacy: Your code and API key stay on your machine
💰 No shared costs: Use your own Anthropic credits
⚡ No rate limits: No shared usage limits with other users
🎯 Full control: Modify, extend, and adapt to your needs
🔧 Fork-friendly: MIT license - use it commercially or personally

🚀 Features

🔍 Comprehensive Analysis: Detects 15+ vulnerability types including reentrancy, access control failures, and integer overflow
🤖 AI-Powered: Uses Claude Sonnet 4 for intelligent analysis beyond simple pattern matching
⚡ Fast Results: Get detailed security reports in under 15 seconds
🎯 Zero False Positives: Focused on real, exploitable vulnerabilities only
📊 Detailed Reports: Interactive vulnerability cards with impact analysis and fix recommendations
💾 Export Reports: Download analysis results as JSON
🎨 Modern UI: Clean, responsive interface built with Tailwind CSS

🏗️ Architecture

graph TB
    A[User] --> B[Next.js Frontend]
    B --> C[Code Editor]
    C --> D[API Route /analyze]
    D --> E[Claude Sonnet 4]
    E --> F[JSON Response]
    F --> D
    D --> G[Results Page]
    G --> H[Vulnerability Cards]
    
    subgraph "Frontend Components"
        C
        G
        H
    end
    
    subgraph "Backend Processing"
        D
        E
    end
    
    style A fill:#e1f5fe
    style E fill:#fff3e0
    style H fill:#f3e5f5

🔧 Tech Stack

Technology	Purpose	Version
Next.js	Full-stack React framework	15.5.4
TypeScript	Type safety and developer experience	5.0+
Claude Sonnet 4	AI-powered security analysis	Latest
Tailwind CSS	Styling and responsive design	3.4+
Lucide React	Modern icon library	Latest
Monaco Editor	Code editor with Solidity syntax highlighting	Latest

📋 Vulnerability Detection

Critical Severity 🔴

Reentrancy: External calls before state updates
Access Control: Missing admin function protection
Delegatecall: Untrusted address delegation
Selfdestruct: Unprotected contract destruction

High Severity 🟠

Unchecked Calls: External calls without return value checks
tx.origin Auth: Phishing-vulnerable authentication
Integer Overflow: Arithmetic issues in Solidity <0.8.0

Medium Severity 🟡

Timestamp Dependence: Block timestamp manipulation
DoS Vectors: Unbounded loops and gas griefing
Front-running: MEV exploitation opportunities

Low/Info Severity 🔵

Floating Pragma: Version range vulnerabilities
Outdated Compiler: Missing security features
Missing Events: Admin action transparency
Gas Optimization: Efficiency improvements

🚀 Quick Start

Prerequisites

Node.js 18+
npm/yarn/pnpm
Anthropic API key (required - see below)

Get Your Anthropic API Key

Before you start, you need your own Anthropic API key:

Visit console.anthropic.com
Sign up or log in to your account
Navigate to API Keys section
Click Create Key
Copy your API key (starts with sk-ant-api03-...)
Keep it safe - you'll need it in the next steps

Note: Anthropic offers free credits for new accounts. Check their pricing at anthropic.com/pricing

Installation

Clone the repository

git clone https://github.com/yourusername/smartcontract-security-scanner.git
cd smartcontract-security-scanner

Install dependencies
```
npm install
```
Set up your API key

Create a .env.local file in the root directory:
```
# On Linux/Mac
touch .env.local

# On Windows (PowerShell)
New-Item .env.local
```
Add your Anthropic API key to .env.local:
```
ANTHROPIC_API_KEY=sk-ant-api03-your-actual-key-here
```
⚠️ Important:
- Replace sk-ant-api03-your-actual-key-here with your real API key
- Never commit .env.local to git (it's already in .gitignore)
- Each user needs their own API key
Run the development server
```
npm run dev
```
Open your browser

Navigate to http://localhost:3000

You should see the Smart Contract Scanner interface ready to use!

📖 Usage

1. Upload or Paste Code

Upload a .sol file or paste Solidity code directly
Use the example contract for testing

2. Analyze Contract

Click "Analyze Contract" to start the security scan
Wait 10-15 seconds for AI analysis

3. Review Results

View security score (0-100)
Examine vulnerability details
Read impact descriptions and recommendations
Download report as JSON

🔄 Analysis Flow

sequenceDiagram
    participant U as User
    participant F as Frontend
    participant A as API Route
    participant C as Claude AI
    participant R as Results
    
    U->>F: Upload Solidity code
    F->>A: POST /api/analyze
    A->>A: Validate code
    A->>C: Send analysis prompt
    C->>C: Analyze vulnerabilities
    C->>A: Return JSON results
    A->>A: Calculate security score
    A->>F: Return analysis data
    F->>R: Display results
    R->>U: Show vulnerability cards

🛠️ Development & Customization

Project Structure

src/
├── app/                    # Next.js App Router
│   ├── api/analyze/        # ⭐ API endpoint - customize analysis logic
│   ├── results/           # Results display page
│   ├── scan/              # Code upload page
│   └── page.tsx           # Landing page
├── components/            # React components
│   ├── ui/                # Reusable UI components
│   ├── CodeEditor.tsx     # Monaco editor wrapper
│   ├── VulnerabilityCard.tsx  # ⭐ Customize vulnerability display
│   └── SeverityBadge.tsx
└── lib/                   # ⭐ Core logic - start customizing here
    ├── claude.ts          # Claude API client
    ├── prompts.ts         # ⭐ Analysis prompts - modify detection logic
    ├── types.ts           # TypeScript definitions
    └── utils.ts           # Helper functions

🔧 How to Extend This Template

1. Customize Vulnerability Detection (Easy)

Edit src/lib/prompts.ts to add your own detection rules:

// Add custom vulnerability types
export function buildAnalysisPrompt(solidityCode: string): string {
  return `
    ... existing prompt ...
    
    # CUSTOM DETECTION RULES
    - Check for flash loan vulnerabilities
    - Detect price oracle manipulation
    - Analyze MEV opportunities
  `;
}

2. Add New Features (Intermediate)

Multi-file analysis: Modify /api/analyze to accept multiple files
Historical tracking: Add database to track vulnerability trends
Custom scoring: Change the security score algorithm in route.ts
Export formats: Add PDF, Markdown, or CSV export options

3. Integrate External Tools (Advanced)

// Example: Integrate with Slither or Mythril
import { execSync } from 'child_process';

async function hybridAnalysis(code: string) {
  const claudeResults = await analyzeContract(code, prompt);
  const slitherResults = execSync('slither analyze.sol').toString();
  // Combine results...
}

4. Build Team Features

Add user authentication (NextAuth.js)
Create shared workspaces
Implement commenting on vulnerabilities
Track remediation status

💡 Feature Ideas to Implement

Here are some ideas to inspire you:

🔍 Analysis Features:

Multi-contract analysis (import resolution)
Gas optimization suggestions
Code quality metrics
Comparison with best practices
Historical vulnerability tracking

🔌 Integrations:

📊 Reporting:

🎓 Educational:

🏢 Enterprise:

Available Scripts

# Development
npm run dev          # Start development server
npm run build        # Build for production
npm run start        # Start production server

# Code Quality
npm run lint         # Run ESLint
npm run type-check   # Run TypeScript compiler

🔒 Security & Privacy

Your Data is Safe

100% Local: Everything runs on your machine - no data sent to external servers (except Anthropic API)
No Storage: Your Solidity code is never stored anywhere
Private API Key: Your API key stays in your .env.local file
No Tracking: No analytics, no telemetry, no data collection

Protect Your API Key

⚠️ NEVER share or commit your API key:

✅ Store it in .env.local (already in .gitignore)
✅ Keep it private and secure
❌ Never commit it to GitHub
❌ Never share it in Discord/Slack/etc.
❌ Never hardcode it in your code

If you accidentally expose your API key:

Go to console.anthropic.com
Revoke the exposed key immediately
Generate a new API key
Update your .env.local file

Cost Control

Each analysis costs approximately $0.01 - $0.03 in API credits
You control your spending through your Anthropic account
Set usage limits in your Anthropic console
Monitor your usage at console.anthropic.com

📊 Performance

Metric	Value
Analysis Time	10-15 seconds
Code Size Limit	50KB
Supported Versions	Solidity 0.4.0+
Vulnerability Types	15+ categories
False Positive Rate	<5%

🔧 Troubleshooting

"API key required" error

Problem: You see an error message about missing API key.

Solution:

Make sure you created .env.local in the root directory (same level as package.json)
Check that your API key is correctly formatted: ANTHROPIC_API_KEY=sk-ant-api03-...
Restart the development server after creating .env.local:
```
# Stop the server (Ctrl+C)
npm run dev
```

"Invalid API key format" error

Problem: The API key format is not recognized.

Solution:

Verify your API key starts with sk-ant-
Make sure there are no extra spaces or quotes in .env.local
Copy the key directly from Anthropic console

Analysis is slow or timing out

Problem: Analysis takes longer than expected.

Solution:

Check your internet connection
Verify your Anthropic account has available credits
Try with a smaller contract first to test

Can't find `.env.local` file

Problem: The file is hidden or not visible.

Solution:

On Windows: Enable "Show hidden files" in File Explorer
On Mac/Linux: The file starts with . so it's hidden by default
Use your code editor (VS Code) to create the file - it will show hidden files

Need help?

If you encounter other issues:

Check the Anthropic Documentation
Open an issue on GitHub
Make sure you're using Node.js 18+

🤝 Contributing & Community

This is a starter template, so we encourage you to:

Fork & Build

Have you built something cool with this template?

We'd love to see what you create! Consider:

Opening a PR to add your project to a "Built with this template" section
Sharing your fork on Twitter/X with #SmartContractScanner
Writing a blog post about your customizations

Share Your Ideas

Found ways to improve the base template?

Open an issue with suggestions
Submit a PR with improvements
Share your custom prompts that worked well

Show Your Work

Built an awesome project? Add it here:

Projects Built With This Template:

Your project could be here! - Fork and customize this template

🌟 Use Cases & Examples

Real-World Applications

For Security Firms:

Customize prompts for your specific audit methodology
Add your branding and custom reporting
Integrate with your internal tools

For DeFi Protocols:

Create protocol-specific security scanners
Add checks for your token standards
Monitor deployed contracts continuously

For Educators:

Build interactive security learning platforms
Create challenges with automatic vulnerability detection
Provide instant feedback to students

For Development Teams:

Integrate into your CI/CD pipeline
Create custom checks for your codebase style
Track security improvements over time

🚀 Next Steps

After setting up your own instance:

Experiment: Try analyzing different contracts to understand the baseline behavior
Customize: Start with small prompt modifications in prompts.ts
Extend: Add your first new feature (maybe a new export format?)
Share: Consider open-sourcing your improvements
Scale: Deploy to Vercel, Railway, or your own infrastructure

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

What this means:

✅ Use it commercially
✅ Modify and distribute
✅ Use it privately
✅ No warranty provided

🙏 Acknowledgments

Anthropic for Claude Sonnet 4 AI capabilities
OpenZeppelin for security best practices reference
Consensys for Solidity security guidelines
SWC Registry for vulnerability classification
The Web3 Security Community for continuous innovation

Built with ❤️ as a starting point for the next generation of smart contract security tools

⭐ Star this repo if you found it useful • 🔀 Fork it to build your own tool • 🐛 Report issues to help improve it

Name		Name	Last commit message	Last commit date
Latest commit History 4 Commits
.vscode		.vscode
public		public
src		src
.gitignore		.gitignore
README.md		README.md
components.json		components.json
eslint.config.mjs		eslint.config.mjs
next.config.ts		next.config.ts
package-lock.json		package-lock.json
package.json		package.json
postcss.config.mjs		postcss.config.mjs
tsconfig.json		tsconfig.json
utils.ts		utils.ts

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Smart Contract Security Scanner - Starter Template

🎯 What is This?

💡 What Can You Build?

🏠 Self-Hosted & Open Source

🚀 Features

🏗️ Architecture

🔧 Tech Stack

📋 Vulnerability Detection

Critical Severity 🔴

High Severity 🟠

Medium Severity 🟡

Low/Info Severity 🔵

🚀 Quick Start

Prerequisites

Get Your Anthropic API Key

Installation

📖 Usage

1. Upload or Paste Code

2. Analyze Contract

3. Review Results

🔄 Analysis Flow

🛠️ Development & Customization

Project Structure

🔧 How to Extend This Template

1. Customize Vulnerability Detection (Easy)

2. Add New Features (Intermediate)

3. Integrate External Tools (Advanced)

4. Build Team Features

💡 Feature Ideas to Implement

Available Scripts

🔒 Security & Privacy

Your Data is Safe

Protect Your API Key

Cost Control

📊 Performance

🔧 Troubleshooting

"API key required" error

"Invalid API key format" error

Analysis is slow or timing out

Can't find .env.local file

Need help?

🤝 Contributing & Community

Fork & Build

Share Your Ideas

Show Your Work

🌟 Use Cases & Examples

Real-World Applications

🚀 Next Steps

📄 License

🙏 Acknowledgments

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