📚 PDFtoEPUB Converter

An enterprise-grade, full-stack web application designed to instantly convert PDF documents into responsive, perfectly formatted EPUB files for e-readers. Built with modern web technologies, this system guarantees zero data loss, intelligent layout extraction, and high-performance concurrent processing.

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🚀 Key Technological Highlights

1. Robust API & Conversion Engine (Python / FastAPI)

The core of the application relies on an asynchronous Python microservice built to handle heavy, concurrent PDF parsing.

• FastAPI Core: Leverages uvicorn and FastAPI for ultra-low latency, async route handling, and highly concurrent multipart file uploads (up to 20MB per request payload limits enforced).
• Intelligent Page-by-Page Extraction (PyMuPDF / fitz): Extracts raw structural text arrays from the document. The system processes PDF geometries (x/y coordinates) to mathematically separate body text from running headers and footers (ignoring the top and bottom 8% vertical margins to strip out repeated author names/page numbers).
• Dynamic E-Book Generation (EbookLib): Recompiles chronological string chunks directly into standard, reflowable EPUB3 architecture. The API enforces strict CSS rules (page-break-before: always;) to perfectly map 1 PDF Page to 1 EPUB Page without compromising the fluid, text-based reading experience.
• Auto-Cleanup Background Tasks: Integrates FastAPI's BackgroundTasks queue to programmatically flush temporary processing directories (tmp) immediately after the FileResponse executes, strictly preventing memory leaks and storage overlap.

2. High-Performance Client Interface (Next.js 14+)

The frontend provides a seamless, App-like (PWA) experience without page reloading or server-side lag.

• Next.js & Turbopack: Bootstrapped via Next.js for SSR/CSR combinations, utilizing Turbopack for near-instant compilation and rendering.
• Dynamic IP Binding: Developed with mobile-testing in mind. Includes intelligent window .hostname polling via XMLHttpRequest to automatically bypass "localhost" restrictions, dynamically targeting local network and cellular network endpoints without code recompilation.
• State Management: Fully client-side state machine (React Hooks) tracking parallel file objects inside an interactive Dropzone. Supports 4 distinct lifecycle queues: idle, converting, success, and error.
• UI/UX Design: Zero CSS frameworks required beyond standard TailwindCSS v4. Implements advanced "Glassmorphism" design paradigms (backdrop-filters) combined with granular micro-animations via Lucide-React.

3. Progressive Web App (PWA) Standards

• Built to function identically to a native iOS/Android application.
• Configured with strict metadata limits and caching layers to be fully installable directly to a mobile device's home screen.

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🌐 Local Development Environment

Prerequisites

• Node.js (v18+)
• Python (v3.11+)

Running the Backend

1. cd backend
2. Create virtual environment: python -m venv venv
3. Activate virtual environment:
   • Mac/Linux: source venv/bin/activate
   • Windows: venv\Scripts\activate
4. Install dependencies: pip install -r requirements.txt
5. Start the FastAPI server (Bind to all IPs for mobile testing):

   uvicorn main:app --host 0.0.0.0 --port 8000 --reload

Running the Frontend

1. cd frontend
2. Install active dependencies: npm install
3. Start the Turbopack server:

   npm run dev

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☁️ Cloud Deployment Architecture

This application utilizes a decoupled, serverless hosting strategy for maximum free-tier scaling and security.

• Frontend Hosting (Vercel): The Next.js client is CI/CD integrated with Vercel edge networks. Ensure the NEXT_PUBLIC_API_URL environment variable is explicitly set to point to the backend provider.
• Backend Hosting (Render.com / AWS): The FastAPI Python engine is deployed natively using Python 3.11 (configured via .python-version explicitly). Requires minimal build triggers: pip install -r requirements.txt and uvicorn main:app --host 0.0.0.0 --port $PORT.