This PDF Signing Tool is a modern, client-side web application that allows users to:

• Upload PDF documents
• Add digital signatures (either drawn or typed)
• Position and resize signatures
• Download signed PDFs

All processing happens in the browser without requiring server-side processing, ensuring document privacy.

Key Features

1. PDF Upload

• Drag and drop interface for easy file selection
• File validation to ensure only PDFs are accepted
• Visual feedback showing the selected file

2. Signature Creation

Two signature methods:

• Draw Signature:
• Canvas-based drawing pad
• Clear button to start over
• Responsive to mouse and touch input
• Type Signature:
• Text input for name entry
• Multiple cursive font options
• Color customization
• Live preview of the signature

3. Signature Positioning

• Visual positioning system with draggable marker
• Precise controls for:
• Page selection (multi-page PDF support)
• X/Y coordinates (percentage-based)
• Signature size adjustment
• Live preview of signature placement

4. PDF Processing

• Uses PDF-Lib library for PDF manipulation
• Preserves original PDF content and formatting
• Adds signature as either:
• Embedded image (for drawn signatures)
• Text element (for typed signatures)

5. Download

• Generates signed PDF with original filename prefixed with “signed_”
• Uses FileSaver.js for reliable downloads

Technical Implementation

Frontend Technologies

• HTML5, CSS3, and JavaScript (ES6)
• Modern CSS with Flexbox and custom properties
• Responsive design that works on desktop and mobile
• Clean, intuitive UI with visual feedback

Key Libraries

• PDF-Lib: Client-side PDF manipulation
• Signature Pad: Canvas-based signature drawing
• FileSaver.js: Client-side file downloading

Security Features

• No server processing – all work happens in the browser
• No document data is transmitted or stored externally
• Clear visual indication of signing process

Usage Scenarios

• Signing contracts and agreements
• Approving documents remotely
• Adding signatures to PDF forms
• Any situation requiring a quick digital signature

Limitations

• Basic signature security (no cryptographic signing)
• Typed signatures use standard PDF fonts (no handwriting simulation)
• Complex PDFs with advanced features may not render perfectly

This tool provides a simple yet effective solution for adding signatures to PDF documents while maintaining privacy through client-side processing.