PixelPress

PixelPress is a local-first image compression app built with Astro, React, and browser-side codecs. You drop in a batch of images, the work happens in a web worker, and you get to compare the results before downloading anything.

There is no upload step and no backend doing secret image work somewhere else. The whole point is to keep it simple: run it locally, compress a pile of images, keep the version that actually looks worth keeping, and move on.

What the app does

• Compresses images in the browser with @jsquash codecs
• Optimizes PNG output with @jsquash/oxipng
• Compresses PNGs more aggressively with imagequant / libimagequant
• Keeps PNG-preserving optimization separate from WebP and AVIF conversion
• Generates multiple candidate variants when that helps
• Lets you compare the original and compressed output side by side
• Keeps the best result by default while still letting you switch between generated versions
• Exports one file at a time or bundles the best results into a zip

Tech stack

• Astro 6 for the site shell and routes (Cloudflare Workers adapter)
• React 19 for the compression workspace
• Tailwind CSS v4 for styling
• Web Workers for codec work and PNG optimization
• imagequant WASM for lossy PNG quantization
• Cloudflare Workers for deployment
• Bun for installs and scripts

Project shape

• src/pages contains the Astro routes
• src/components/app contains the React compression UI
• src/lib/workers contains the compression worker
• src/lib/codecs contains the codec helpers
• src/lib/utils contains shared types, presets, formatting, and storage helpers
• src/content/changelog contains changelog entries

The app now lives at /. The old /app path is redirected for compatibility.

Getting started

Use Node 24 and Bun.

node --version
bun install
bun run dev

The dev server runs on http://localhost:4321.

The default deployment target in this repo is Cloudflare Workers at https://pixelpress.workers.dev. If you attach a custom domain, update Astro site in astro.config.mjs so canonical URLs point at the final hostname.

Commands

bun run dev
bun run check
bun run build
bun run preview
bun run deploy

Notes

• bun run check runs both linting and astro check
• bun run preview uses Astro's Cloudflare-aware preview runtime after a build
• Compression stays client-side, including PNG optimization
• PNG now has two explicit modes:
  • Optimized PNG is lossless and uses @jsquash/oxipng
  • Compressed PNG keeps PNG output but uses imagequant / libimagequant to reduce colors for better savings
• Last-used settings are stored in localStorage
• SharedArrayBuffer support is enabled in production through COOP/COEP headers in Astro middleware (src/middleware.ts)

Licensing

PixelPress is licensed under GPL-3.0-or-later.

Lossy PNG compression is powered by imagequant, which wraps libimagequant for browser/WASM usage under GPL-compatible terms. See THIRD_PARTY_NOTICES.md for package references used by this repo.

Why it exists

This started from a pretty ordinary annoyance: a lot of image tools are either too limited, too fussy, or too eager to push you toward an upload flow. PixelPress is meant to feel lighter than that. Open it, drop files in, compare the outputs, download the ones you want, done.