Express PDF Watermark API

A simple Express.js API for embedding watermarks on PDF files using pdf-lib and Multer. This project demonstrates how to apply forensic watermarks with user details (or unique identifiers) to each page of a PDF, helping deter unauthorized distribution while maintaining user privacy.

Features

• PDF Upload: Accepts PDF files through a REST API endpoint.
• Dynamic Watermarking: Applies a customizable watermark on every page of the uploaded PDF.
• User Data Integration: Incorporates user details such as name, email, phone, and IP into the watermark text.
• Simple & Extendable: Built with Express.js, making it easy to integrate or extend for your needs.

Prerequisites

• Node.js (v12 or later)
• npm

Installation

Follow these step-by-step instructions to get the project running on your local machine:

1. Clone the repository:

   git clone https://github.com/yourusername/express-pdf-watermark-api.git
   cd express-pdf-watermark-api

2. Install dependencies:

   npm install

3. Project Structure:

   • server.js – The main Express server file containing the watermarking API endpoint.
   • package.json – Contains project metadata and dependencies.

Usage

Running the Server

Start the Express server by running:

node server.js

By default, the server listens on port 3000. You should see a message similar to:

Server started on port 3000

Testing the API with Postman

To test the watermark API endpoint using Postman:

1. Create a New Request:

   • Set the HTTP method to POST.
   • Enter the URL: http://localhost:3000/watermark.

2. Configure the Request Body:

   • Click on the Body tab.
   • Select form-data.
   • Add the following keys:
     • pdf: Change the type to File and select a PDF file from your computer.
     • name: Enter a sample name (e.g., John Doe).
     • email: Enter a sample email (e.g., john@example.com).
     • phone: Enter a sample phone number (e.g., 1234567890).
     • ip: Enter a sample IP address (e.g., 192.168.1.1).

3. Send the Request:

   • Click the Send button.
   • The API processes the PDF and returns the watermarked PDF file.
   • You can use the Save Response option to download and view the watermarked PDF.

Customization

You can modify the watermark's content and style by editing the code in server.js. For example, you might change the text formatting, position, rotation angle, or opacity to suit your needs. If you prefer not to expose full personal data, consider using a unique transaction identifier instead.

Contributing

Contributions, bug reports, and feature requests are welcome! Feel free to open issues or submit pull requests.

License

This project is licensed under the MIT License.

Disclaimer

Embedding personal data directly into documents may have privacy implications. Evaluate your approach and consider using less intrusive methods (such as unique transaction IDs) if privacy is a major concern.