towebp - Lazy webp converter

CLI tool and native macOS app to batch convert images to WebP format. Handles single files, multiple files, and entire directories with concurrent processing, atomic writes, and mtime-based skip logic.

Quick Start

npx towebp photo.png

Converts photo.png to photo.webp in the same directory.

Install

Global (adds towebp to your PATH):

npm install -g towebp

Run without installing (via npx):

npx towebp photo.png

From source:

git clone https://github.com/keiver/towebp.git
cd towebp
npm install && npm run build && npm link

Usage

# Convert a single file (output next to source)
towebp photo.png

# Convert multiple files at once
towebp photo.png banner.jpg logo.gif

# Convert all images in a directory
towebp images/

# Convert to a separate output directory
towebp -o output/ images/

# Custom quality (1-100, default: 90)
towebp -q 80 photo.png

# Recursive subdirectory processing
towebp -r images/

# Combine flags
towebp -q 75 -r -o dist/ src/assets/

Options

Flag	Description
-q, --quality <n>	WebP quality 1-100 (default: 90)
-o, --output <dir>	Output directory (default: next to source)
-r, --recursive	Process subdirectories recursively
-h, --help	Show help message
-v, --version	Show version number

Features

• Accepts multiple input files and directories in a single command
• Skips files that haven't changed (compares mtime)
• Gracefully skips non-image files with a warning
• Atomic writes via temp file + rename
• Concurrent processing (up to 4 workers)
• Color space conversion (display-p3 / RGB to sRGB)
• Auto-rotation based on EXIF data
• Recursive subdirectory support with mirrored output structure

Supported Formats

JPG, JPEG, PNG, GIF, BMP, TIFF, WebP

macOS App — Lazy Webp

Native SwiftUI app that wraps the CLI. Drag and drop images or folders to convert them — output is generated next to each source file.

Requirements

• macOS 14+
• Swift 6.2+
• The towebp CLI must be installed and available in your PATH

Run in development

cd app
swift run

Install to /Applications

cd app
./install-app.sh

This builds a release binary, creates an app bundle at /Applications/Lazy Webp.app (dev.keiver.lazywebp), and signs it locally.

App Features

• Drag-and-drop files and folders
• File picker dialog
• Quality slider (1-100)
• Per-file size and savings display
• Live progress tracking with cancel support
• Always-on-top floating window
• Menu bar icon with quick access
• Launch at login option
• Install to /Applications from the menu bar

Requirements

Component	Requires
CLI	Node.js 18+, Sharp
macOS App	macOS 14+, Swift 6.2+

npm Scripts

Script	Description
npm run dev	Run directly from TypeScript source
npm run build	Compile to JavaScript in dist/
npm start	Run compiled build
npm test	Run tests
npm run test:watch	Run tests in watch mode

License

MIT