PdfMerger

PdfMerger is a PDF manipulation tool available both as a command-line interface (inspired by pdftk) and as a web application. Written in Python, it provides advanced features for merging, splitting, encryption, and form/attachment management.

Table of Contents

• Features
• Requirements
• Installation
• Web Interface
• Command-Line Usage
  • General Syntax
  • Main Operations
  • Encryption
  • Other Options
  • Advanced Examples
• Exit Codes
• Known Limitations
• Differences from Original pdftk
• License
• Version
• Contributing

Features

• Merge PDFs - Combine multiple PDF files with custom page ranges
• Split PDFs - Extract individual pages or burst into single-page files
• Encryption - Password-protect PDFs with 128-bit encryption and granular permissions
• Form Handling - Fill PDF forms using FDF data with optional flattening
• Attachments - Attach files to PDFs or extract embedded attachments
• Metadata - Read, export, and update PDF metadata
• Background - Apply background watermarks to PDF pages
• Repair - Attempt to recover corrupted PDF files

Requirements

• Python 3.8 or higher
• Dependencies (see requirements.txt):
  • pypdf[crypto]>=3.17.1
  • PyMuPDF>=1.23.8
  • typing-extensions>=4.9.0

Installation

1. Clone or download the repository:

   git clone <repository-url>
   cd PdfMerger

2. Install dependencies:

   pip install -r requirements.txt

Web Interface

PdfMerger includes a Flask-based web interface for easy PDF merging and splitting without using the command line.

Starting the Web Server

python app.py

The server will start on http://localhost:5000 (or http://0.0.0.0:5000 for network access).

Features

• Merge PDFs - Upload multiple PDF files and combine them into a single document
• Split PDF - Upload a single PDF and split it into individual pages (downloaded as ZIP)
• Drag & Drop - Intuitive drag-and-drop file upload
• Responsive Design - Bootstrap-styled interface that works on desktop and mobile

API Endpoints

Endpoint	Method	Description
/	GET	Web interface homepage
/merge	POST	Merge multiple PDFs
/split	POST	Split a PDF into pages
/download/<filename>	GET	Download a processed file
/cleanup	POST	Clean up temporary files

Request Format

Merge:

curl -X POST -F "files=@file1.pdf" -F "files=@file2.pdf" http://localhost:5000/merge

Split:

curl -X POST -F "file=@document.pdf" http://localhost:5000/split

Configuration

Variable	Default	Description
MAX_CONTENT_LENGTH	50MB	Maximum upload size
UPLOAD_FOLDER	temp dir	Temporary upload location
OUTPUT_FOLDER	temp dir	Output file location

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Command-Line Usage

General Syntax

python pdfmerger.py <input> [<operation>] [output <file>] [options]

Main Operations

1. Merge PDFs (cat)

Combine multiple PDFs into a single file:

# Simple merge
python pdfmerger.py file1.pdf file2.pdf cat output merged.pdf

# With page ranges
python pdfmerger.py A=doc1.pdf B=doc2.pdf cat A1-3 B5-10 output result.pdf

# Pages to end
python pdfmerger.py A=doc.pdf cat A5-end output extracted.pdf

2. Split PDFs (burst)

Split a PDF into individual pages:

python pdfmerger.py document.pdf burst output page_%04d.pdf

Creates a doc_data.txt file with metadata.

3. Extract Metadata (dump_data)

python pdfmerger.py input.pdf dump_data output metadata.txt

4. Extract Form Field Information (dump_data_fields)

python pdfmerger.py form.pdf dump_data_fields output fields.txt

5. Apply Background (background)

python pdfmerger.py input.pdf background watermark.pdf output result.pdf

6. Fill Form (fill_form)

python pdfmerger.py form.pdf fill_form data.fdf output filled.pdf flatten

The flatten option flattens form fields after filling.

7. Attach Files (attach_files)

# Attach at document level
python pdfmerger.py input.pdf attach_files attachment1.txt attachment2.pdf output output.pdf

# Attach to a specific page
python pdfmerger.py input.pdf attach_files file.txt to_page 5 output output.pdf

8. Extract Attachments (unpack_files)

python pdfmerger.py input.pdf unpack_files output ./attachments_folder/

9. Update Metadata (update_info)

python pdfmerger.py input.pdf update_info info.json output output.pdf

info.json format:

{
  "/Title": "Document Title",
  "/Author": "Author Name",
  "/Subject": "Document Subject",
  "/Keywords": "keyword1, keyword2",
  "/Creator": "Creator Name",
  "/Producer": "Producer Name"
}

Encryption

Password-Protect a PDF

python pdfmerger.py input.pdf output protected.pdf encrypt_128bit owner_pw owner_password user_pw user_password

Specify Permissions

python pdfmerger.py input.pdf output protected.pdf encrypt_128bit allow Printing CopyContents

Available permissions:

• Printing - Print the document
• DegradedPrinting - Print at degraded quality
• ModifyContents - Modify document contents
• Assembly - Assemble the document
• CopyContents - Copy contents
• ScreenReaders - Screen reader access
• ModifyAnnotations - Modify annotations
• FillIn - Fill form fields
• AllFeatures - All features enabled

Other Options

Option	Description
flatten	Flatten form fields
compress	Compress streams (default)
uncompress	Decompress streams
verbose	Show verbose output
repair	Attempt to repair corrupted PDFs
do_ask	Enable interactive input (default)
dont_ask	Disable interactive input

Advanced Examples

Merge with Encryption

python pdfmerger.py A=chapter1.pdf B=chapter2.pdf cat output book.pdf encrypt_128bit owner_pw admin user_pw reader allow Printing

Repair a Corrupted PDF

python pdfmerger.py corrupted.pdf output repaired.pdf repair

Filter Mode (No Operation)

Apply only output options to a single PDF:

python pdfmerger.py input.pdf output output.pdf flatten compress

Exit Codes

Code	Description
0	Success
1	Error (missing input, wrong password, etc.)

Web Interface Dependencies

The web interface requires additional packages:

• flask
• flask-cors
• werkzeug

Install them with:

pip install flask flask-cors

Known Limitations

• The fill_form operation requires FDF files in simplified format
• background uses PyMuPDF and may not preserve all interactive features
• Some heavily corrupted PDFs may not be repairable

Differences from Original pdftk

• Implemented in pure Python (with PyMuPDF support for advanced operations)
• Some FDF operations are simplified
• Native Unicode support in metadata
• Cross-platform compatibility

License

Free software with no warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Version

2.0.0 - Copyright (C) 2025

Contributing

Contributions are welcome! To report bugs or request features, please open an issue.

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Note: This project is not affiliated with or endorsed by the original pdftk authors.