KleinPDF - A tiny PDF Compression Desktop App

A high-performance PDF compression desktop application built with Wails (Go + Web) and Preact frontend. macOS-only (Intel + Apple Silicon) with Ghostscript bundled inside the app.

Screenshot

🚀 Features

• 📄 Advanced PDF Compression: Compression using embedded Ghostscript
• 🖥️ Native Desktop Experience: Built with Wails for seamless desktop integration
• 📁 Batch Processing: Compress multiple PDF files simultaneously with concurrent processing
• ⚙️ Configurable Settings: Multiple compression levels and advanced options
• 📊 Statistics Tracking: Session and lifetime statistics for files compressed and data saved

🛠️ Tech Stack

• Backend: Go 1.25 with Wails v2 framework
• Frontend: Preact + TypeScript + Vite for fast, lightweight UI
• Desktop Runtime: Wails (native Go binaries)
• PDF Compression: Ghostscript 10.05.1 (embedded binary)
• Database: SQLite with GORM for data persistence
• Styling: Tailwind CSS with custom PDF-themed design
• Build Tools: Wails CLI, Vite, Go modules
• Package Manager: pnpm for frontend dependencies

⚡ Performance Features

• Concurrent Processing: Multi-threaded compression (up to 8 cores)
• Direct File Processing: No temporary file copying - Ghostscript reads original and writes compressed directly
• Bundle Size: Small native binary with embedded resources
• Startup Time: Native binary execution with minimal overhead

🚀 Quick Start

Prerequisites (macOS)

• Go 1.25 or later
• Node.js 19+
• pnpm (recommended) or npm
• Wails CLI (go install github.com/wailsapp/wails/v2/cmd/wails@latest)

Installation

1. Clone the repository:

   git clone <repository-url>
   cd compressor

2. Install dependencies:

   go mod tidy
   cd frontend && pnpm install && cd ..

Development

Start the application in development mode:

wails dev

This will:

• Start the Go backend integrated with Wails
• Launch the native application with hot reload
• Enable frontend development tools

Generate bindings after Go changes:

wails generate module

🚀 Production Build

wails build

This creates a macOS app in the build/ directory.

📦 Ghostscript Binary Management

This app uses architecture-specific Ghostscript binaries directly embedded from GitHub releases. The binary is automatically downloaded and embedded during build time using Go's go:generate feature.

Binary Generation

The appropriate binary for your system architecture is automatically downloaded during build:

# Generate the binary (happens automatically during build)
go generate ./internal/binary

Supported architectures:

• Apple Silicon (arm64): ghostscript-10.05.1-macos-arm64
• Intel Macs (amd64): ghostscript-10.05.1-macos-x86_64

The binary is embedded directly into the application using Go's embed package, eliminating the need for complex archive extraction.