Pedantic Picture Packer - Image Compression for Thunderbird

Thunderbird add-on for image compression in emails (attachments + inline images)
Runs locally via WebAssembly → images never leave your device
Open source, available for Thunderbird 115+
Supports 9 languages

State-of-the-art algorithms
PNG pipeline:
- pngquant: state-of-the-art algorithm for visually lossless palette reduction
- followed by oxipng: heuristically optimal PNG compression → major savings for screenshots
JPEG:
- Compression with JPEGli, saves ~30% compared to other JPEG encoders like Thunderbird’s built-in MozJPEG
Automatic optimizations:
- Converts PNG → JPG if smaller
- Resizes to match HTML inline dimensions
Format-specific resize algorithms:
- PNG: Mitchell
- JPEG: Lanczos

Compresses PNG & JPEG without visible quality loss
Removes images from quoted emails (optionally completely or replaced with placeholders)
Automatically removes tracking pixels
Quick menu per email with flexible actions
Settings can be saved or executed instantly
Images can be excluded from future compression (e.g. signatures)

Compression templates:
- Create, import, export
- Automatically applied based on image type (attachments, inline, quoted)
Repeat actions freely (compress, undo, refine templates)
Download optimized images for external use (e.g. websites)
Removes unnecessary images first → saves processing time
Prevents double compression of already processed files
Keeps original if compression results in a larger file