PDF Tools - Merge & Edit PDFs Online

A powerful web application built with Flask that allows users to merge multiple PDF files and edit existing PDFs by removing or inserting pages. Features a clean, modern interface with easy-to-use tools for all your PDF needs.

🚀 Features

📄 PDF Merger

• Multiple PDF Upload: Upload and merge 2-50 PDF files at once
• Large File Support: Handle PDFs up to 100MB per file (500MB total)
• Duplicate File Support: Upload the same PDF file multiple times in different positions
• Flexible Ordering: Files are merged in the order they are uploaded
• Progress Indicators: Real-time upload and merge progress tracking
• Chunked Upload: Optimized handling for large files
• Download Merged PDF: Get your combined PDF instantly

✂️ PDF Editor (Remove/Insert Pages)

• Page Preview: View all pages as thumbnails before editing
• Large PDF Support: Edit PDFs up to 100MB with optimized loading
• Remove Pages: Click the "- Remove" button to delete unwanted pages
• Insert Pages: Click the "+ Insert After" button to add new PDF pages at any position
• Drag & Drop Reordering: Rearrange pages by dragging them
• Multiple Insertions: Insert multiple PDF files at different positions
• Visual Feedback: See which pages are marked for removal in real-time
• Progress Tracking: Visual progress for uploads and edits
• Download Edited PDF: Get your modified PDF with all changes applied

🎨 User Interface

• Clean Design: Professional, light-colored interface without gradients
• Responsive Layout: Works perfectly on desktop, tablet, and mobile devices
• Help System: Built-in help button (?) with detailed usage instructions
• Easy Navigation: Back buttons on every page for seamless navigation
• Progress Bars: Real-time visual feedback for all operations
• File Size Validation: Automatic checking of file sizes before upload
• Success Pages: Clear confirmation pages after operations complete
• Error Handling: User-friendly error messages with helpful guidance

📁 Project Structure

pdf-merger/
├── api/
│   └── app.py                  # Main Flask application with all routes
├── templates/
│   ├── index.html              # Home page with feature selection and help
│   ├── upload.html             # File upload interface for merging
│   ├── result.html             # Success page for merged PDFs
│   ├── upload_for_edit.html    # PDF upload page for editing
│   ├── edit_pages.html         # Page editor with preview and controls
│   └── edit_success.html       # Success page for edited PDFs
├── uploads/                    # Temporary upload directory
├── merged/                     # Output directory for merged files
├── edit_sessions/              # Temporary storage for editing sessions
├── requirements.txt            # Python dependencies
├── vercel.json                 # Vercel deployment configuration
├── LICENSE                     # MIT License
└── README.md                   # This file

Installation

Local Development

1. Clone the repository:

   git clone <repository-url>
   cd pdf-merger

2. Create a virtual environment:

   python -m venv venv

3. Activate the virtual environment:

   • Windows:

     venv\Scripts\activate

   • macOS/Linux:

     source venv/bin/activate

4. Install dependencies:

   pip install -r requirements.txt

5. Run the application:

   python api/app.py

6. Access the application: Open your browser and navigate to http://localhost:5000

Dependencies

The application requires the following Python packages:

• Flask: Web framework for building the application
• PyPDF2: Library for PDF manipulation and merging
• PyMuPDF (fitz): High-performance PDF rendering for page previews
• Pillow: Python Imaging Library for image processing
• Werkzeug: WSGI utility library (included with Flask)

📖 Usage

Merging PDFs

1. Select Feature: Click "📄 Merge Multiple PDFs" on the home page
2. Enter Count: Specify how many PDF files you want to merge (2-50)
3. Upload Files: Select PDF files for each slot
   • You can upload the same file multiple times if needed
   • Files will be merged in the order of the slots
4. Merge: Click "Merge PDFs" to combine them
5. Download: Download your merged PDF or start a new merge

Editing PDFs (Remove/Insert Pages)

1. Select Feature: Click "✂️ Edit PDF (Remove/Insert Pages)" on the home page
2. Upload PDF: Select the PDF file you want to edit
3. View Pages: All pages will be displayed as thumbnails
4. Remove Pages:
   • Click the "- Remove" button on any page to mark it for removal
   • Click again to undo the removal
5. Insert Pages:
   • Click the "+ Insert After" button on any page
   • Upload one or more PDF files to insert at that position
   • You can insert at multiple positions
6. Apply Changes: Click "Apply Changes & Download"
7. Download: Download your edited PDF

Getting Help

• Click the "?" button in the top-right corner of the home page
• Read the detailed instructions for each feature
• Learn tips and best practices

🔌 API Endpoints

Merging Routes

• GET /: Home page with feature selection
• POST /: Process file count and redirect to upload page
• POST /merge: Handle PDF file uploads and merging
• GET /download: Download the merged PDF file
• GET /restart: Return to the home page for a new merge

Editing Routes

• GET /edit-mode: Show PDF upload page for editing
• POST /process-upload-for-edit: Process uploaded PDF and create editing session
• GET /page-image/<session_id>/<page_num>: Generate and serve page preview images
• POST /apply-edits: Apply page removals and insertions
• GET /download-edited/<session_id>: Download the edited PDF file

Deployment

Vercel Deployment

The application is configured for Vercel deployment using the vercel.json configuration file:

{
    "version": 2,
    "builds": [
      {
        "src": "api/app.py",
        "use": "@vercel/python"
      }
    ],
    "routes": [
      {
        "src": "/(.*)",
        "dest": "api/app.py"
      }
    ]
}

To deploy on Vercel:

1. Install Vercel CLI:

   npm i -g vercel

2. Deploy:

   vercel

3. Follow the prompts to configure your deployment

🔧 Technical Details

File Handling

• Merging: Uploaded files stored in /tmp/uploads, merged files in /tmp/merged
• Editing: Session-based storage in /tmp/edit_sessions with unique session IDs
• Auto Cleanup: All uploaded files are automatically deleted after processing
• Unique Filenames: UUID-based naming prevents conflicts when uploading duplicate files
• Chunked Processing: Large files processed in 8KB chunks for memory efficiency
• Session Cleanup: Edit sessions automatically cleaned up after download

PDF Processing

• Merging: Uses PyPDF2's PdfMerger and PdfWriter for efficient combining
• Page Extraction: PyPDF2's PdfReader for page-level manipulation
• Image Rendering: PyMuPDF (fitz) renders PDF pages as JPEG thumbnails
• Optimization: 0.8x zoom and 60% JPEG quality for fast loading of large PDFs
• Large File Handling: Optimized processing for PDFs up to 100MB
• Progressive Loading: Adaptive delay based on PDF size (200-250ms per page)

Security & Performance

• File Validation: Only PDF files accepted with size limits (100MB per file, 500MB total)
• Size Checking: Pre-upload validation prevents oversized files
• Session Isolation: Each editing session has a unique ID with sanitized filenames
• Directory Traversal Protection: All filenames sanitized using secure_filename()
• No Persistent Storage: Files deleted immediately after download
• Progressive Loading: Page images load sequentially to avoid server overload
• Error Recovery: Retry mechanism for failed page loads with user-friendly messages
• Serverless Ready: Optimized for Vercel's serverless functions with 500MB limit
• Memory Management: Chunked file reading/writing for large files

Browser Features

• Modern CSS: Clean, professional design without gradients
• Responsive Grid: Adapts to any screen size
• Smooth Animations: Fade-in effects and hover transitions
• Custom Scrollbars: Styled scrollbars for better UX
• Modal System: Help popup with keyboard shortcuts (ESC to close)
• Lazy Loading: Progressive image loading for better performance

⚠️ Limitations

• File Count: Maximum 50 PDFs can be merged at once
• File Size: 100MB per individual file, 500MB total for merging
• Processing Time: Large PDFs may take longer to process in serverless environments
• Page Previews: Generated on-demand with progressive loading for better performance
• No Password Support: Cannot process password-protected PDFs
• Temporary Storage: Files are not permanently stored, download immediately
• No Encryption: Edited/merged PDFs are not encrypted
• Serverless Timeout: Very large operations may timeout on some hosting platforms

🛠️ Future Enhancements

Potential features for future development:

• Password-protected PDF support
• Page rotation functionality
• Page reordering (drag and drop)
• PDF compression options
• Watermark addition
• PDF to image conversion
• Batch processing
• Cloud storage integration

🤝 Contributing

Contributions are welcome! To contribute:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📝 License

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

🙏 Acknowledgments

• Flask - Web framework
• PyPDF2 - PDF manipulation library
• PyMuPDF - Fast PDF rendering
• Vercel - Deployment platform

📧 Support

If you encounter any issues or have questions:

• Open an issue on GitHub
• Check the built-in help (? button) on the website

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Live Demo: https://pdf-merger-eta-rust.vercel.app/