FactCheck App

Professional PDF Fact-Checking Application — Extract and verify claims from documents using AI-powered analysis and live web search.

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🎯 Overview

FactCheck App is a full-stack application that:

• Accepts PDF uploads with intelligent drag-and-drop interface
• Extracts verifiable claims (statistics, dates, financial & technical figures) using advanced NLP
• Verifies claims against live web sources via multiple search APIs
• Provides verdicts per claim:
  • ✅ Verified — Multiple reliable sources confirm the claim
  • ⚠️ Inaccurate — Outdated or conflicting evidence found
  • ❌ False — No credible evidence found

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🏗️ Architecture

Tech Stack

• Frontend: React 19 + Vite + TypeScript
• Backend: Cloudflare Workers + Hono framework
• Search Engines:
  • SearXNG (recommended - open source)
  • Brave Search API (commercial alternative)
  • Firecrawl API (web scraping fallback)
• PDF Processing: pdfjs-dist (client-side)

Project Structure

factcheck-app/
├── src/                          # React frontend
│   ├── App.tsx                   # Main application component
│   ├── App.css                   # Styling
│   ├── lib/
│   │   ├── pdf.ts               # PDF extraction logic
│   │   ├── types.ts             # TypeScript interfaces
│   │   └── ...
│   ├── main.tsx
│   └── index.css
├── worker/                       # Cloudflare Worker backend
│   ├── src/
│   │   ├── index.ts             # Hono API server
│   │   └── lib/
│   │       ├── claim-extractor.ts
│   │       ├── verifier.ts
│   │       ├── brave.ts
│   │       ├── firecrawl.ts
│   │       └── searxng.ts
│   ├── wrangler.jsonc           # Cloudflare config
│   └── package.json
├── package.json
├── vite.config.ts
└── README.md

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🚀 Quick Start

Prerequisites

• Node.js v20+ (Download)
• npm v10+ (comes with Node)

Installation

# Clone repository
git clone https://github.com/yourusername/factcheck-app.git
cd factcheck-app

# Install dependencies (root + worker)
npm install

Development

Option 1: Run Everything

npm run dev

This starts both the frontend and worker concurrently:

• Frontend: http://localhost:5173
• Worker API: http://localhost:8787

Option 2: Run Separately

# Terminal 1 - Frontend
npm run dev:web

# Terminal 2 - Backend Worker
npm run dev:worker

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⚙️ Configuration

Frontend Environment

Create .env from .env.example:

cp .env.example .env

Set your API endpoint:

VITE_API_BASE_URL=http://localhost:8787

Backend Search Configuration

Edit worker/wrangler.jsonc to configure search provider:

Option A: SearXNG (Recommended - Open Source)

"vars": {
  "SEARXNG_URL": "https://your-searxng-instance.com"
}

Option B: Brave Search API

"vars": {
  "BRAVE_API_KEY": "your_brave_api_key"
}

Get free tier at brave.com

Option C: Firecrawl API

"vars": {
  "FIRECRAWL_API_KEY": "your_firecrawl_key"
}

Get free tier at firecrawl.dev

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📦 Build & Test

Build for Production

npm run build

Outputs:

• dist/ — Built frontend (ready for Cloudflare Pages)
• worker/dist/ — Built worker code

Run Tests

npm test

Tests cover:

• Claim extraction accuracy
• Verdict scoring logic
• API integration

Lint Code

npm run lint

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🌐 Deployment

Deploy Backend (Cloudflare Workers)

cd worker

# Authenticate with Cloudflare
wrangler login

# Deploy
npm run deploy

Note your Worker URL (e.g., https://factcheck-api.your-account.workers.dev)

Deploy Frontend (Cloudflare Pages)

Option 1: CLI

npm run build
wrangler pages deploy dist/

Option 2: GitHub Integration

1. Push to GitHub
2. Connect repository to Cloudflare Pages
3. Set VITE_API_BASE_URL environment variable
4. Pages auto-deploys on push

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🔒 Security

Best Practices

✅ Implemented:

• Input validation on all form fields
• CORS headers properly configured
• Environment variables for sensitive data
• Client-side PDF processing (no uploads to servers)
• TypeScript for type safety

⚠️ Configuration:

• Rotate API keys regularly
• Use .env files (never commit .env to git)
• Enable Cloudflare DDoS protection
• Monitor worker logs for suspicious activity

See SECURITY.md for detailed security guidelines.

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📋 API Documentation

POST /api/analyze

Request:

multipart/form-data
- pdf: File              # PDF document
- extractedText: string  # Pre-extracted text (optional)

Response:

{
  "id": "uuid",
  "results": [
    {
      "claim": {
        "id": "unique_id",
        "text": "Global AI market reached $150B in 2023",
        "numbers": ["150"],
        "years": ["2023"]
      },
      "verdict": "verified",
      "confidence": 0.92,
      "evidence": [
        {
          "title": "Global AI Market Report 2023",
          "url": "https://example.com/ai-market",
          "snippet": "The global artificial intelligence market...",
          "matchedNumbers": ["150"]
        }
      ]
    }
  ],
  "warning": null
}

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📊 Performance

• PDF Processing: ~2-5s (client-side)
• Claim Extraction: ~3-8s (depends on document length)
• Verification: ~2-3s per claim (parallel)
• Total: Typically 10-20s for average PDF

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🤝 Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Areas for contribution:

• Additional search providers integration
• Improved claim extraction models
• UI/UX enhancements
• Documentation improvements
• Test coverage expansion

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📜 License

MIT License — see LICENSE file for details.

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👤 Author

@PARASAGARWAL

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🙏 Acknowledgments

Built with:

• Cloudflare Workers — Serverless compute
• Hono — Lightweight web framework
• React — UI library
• Vite — Frontend tooling

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📞 Support

• 📖 Documentation
• 🐛 Report Issues
• 💬 Discussions

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Last Updated: May 2026 | Status: Production Ready ✨