Compressor

The image-compression tool in the Lessly family of small in-browser utilities.

100% client-side. Compress JPEG, PNG, WebP, AVIF, HEIC, and GIF in your browser — no upload, no signup, no server.

Live: https://allless.github.io/compressor/ (moving to compressor.lessly.me once the domain is set up)

Stack

• Preact — UI framework
• jSquash — WASM image codecs (MozJPEG, OxiPNG, libwebp, libavif)
• libheif-js — HEIC/HEIF decode (LGPL-3.0, lazy-loaded)
• gifsicle-wasm-browser — animated GIF re-optimization (MIT)
• client-zip — batch ZIP download (MIT, streaming)
• Vite — build tool
• TypeScript — strict mode

How it works

1. Drop one or more images
2. Choose output format and quality (or accept the defaults)
3. WASM codecs compress locally
4. Download — single file, or ZIP for batch

Files never leave the browser. Everything runs on your machine.

Development

pnpm install
pnpm dev           # dev server on localhost:5173
pnpm test          # run tests
pnpm build         # production build to dist/
pnpm gen:routes    # regenerate SEO routes + sitemap

Roadmap

See progress.md for the working tracker. Highlights still pending:

• Resize before encode
• EXIF strip / preserve toggle
• JPEG XL (@jsquash/jxl)
• PNG re-optimization via @jsquash/oxipng
• Inline preview in batch rows
• Eventually: a sibling video compressor at video.lessly.me (mediabunny + WebCodecs)