DARKROOM — image resize & format conversion, done in your browser

RESIZE ✦ CONVERT ✦ BATCH ✦ NO SERVER ✦ NO UPLOAD ✦ PRIVACY FIRST ✦ SINGLE HTML ✦ FREE ✦ OPEN SOURCE ✦ RESIZE ✦ CONVERT ✦ BATCH ✦ NO SERVER ✦ NO UPLOAD ✦ PRIVACY FIRST ✦ SINGLE HTML ✦ FREE ✦ OPEN SOURCE ✦ 

암실

D A R K R O O M

Image resize · format conversion · batch processing — all inside your browser

LIVE DEMO GitHub Pages

🔗 Open in new tab 📦 GitHub source

Firing up Photoshop just to shrink one photo? Hunting for websites every time you need to batch-convert images to WebP?

DARKROOM is an image resizer & converter that runs from a single HTML file. Files are never uploaded anywhere — every conversion happens inside your browser. Internet down, someone else's server on fire, whatever: your photos never leave your computer.

FEATURES

📐

Resize

Presets (Full HD · web · thumbnail) / percent / custom. Lock the aspect ratio and one field is enough.

🔄

Format conversion

JPG ↔ PNG ↔ WebP. Quality slider for file size. Transparent backgrounds get a fill color when going to JPEG.

📚

Batch processing

Drag in as many as you want. Change a setting and everything re-converts instantly. Download everything as one ZIP.

🔍

Side-by-side compare

Click a thumbnail to see original vs converted side by side, resolution and file size included.

🔒

100% local

No server traffic. Files never leave your machine. Works without an internet connection.

📄

Single HTML

No installation. One HTML file and you're done. Carry it on a USB stick anywhere.

HOW TO USE — 3 STEPS

01

Drop images

Drag files in or click to select. Multiple at once. JPG · PNG · WebP · GIF · BMP · SVG supported.

02

Configure in the side panel

Size (preset · percent · custom) → format (JPEG · PNG · WebP) → quality → naming rule. Change anything and it re-converts immediately.

03

Download

Save individually or grab the 📦 whole ZIP. Sizes are appended to filenames automatically (e.g. photo_800x600.jpg).

SPEC

Form	Single HTML (36KB) — no install, no dependencies
Formats	Input: JPG · PNG · WebP · GIF · BMP · SVG · AVIF / Output: JPEG · PNG · WebP
Resize modes	Original / 7 presets / percent / custom (aspect lock, cover · contain · exact)
Batch	Unlimited multi-file, auto re-convert on setting change, ZIP download
Privacy	Zero server traffic. All processing local. Works offline.
Browsers	Chrome · Edge · Firefox · Safari (Canvas API + createImageBitmap)
License	MIT — use, modify, distribute freely

DESIGN NOTE

A "photo developing lab" concept. A dark room where only the safelight glows red. The metaphor of "developing" images runs through the whole UI.

🔴 safelight pulse 🎞️ film strip decorations ✨ film grain noise 📐 Black Han Sans + IBM Plex

Start developing now

🔗 Open DARKROOM 📦 GitHub

OPENSOURCE FACTORY · SINGLE HTML · NO SERVER · MIT LICENSE

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