A photo straight from a phone or camera is typically 3–10 MB. Most of that weight is detail your eye will never notice — and it is what makes a web page crawl and a disk fill up.
Cinch re-encodes those files with a modern codec and hands them back at a fraction of the size. A typical photo comes out 85–95% smaller with no visible change. Point it at a folder, press one button, and the originals are left untouched.
It runs entirely on your own machine. Nothing is uploaded anywhere.
Real example. The logo above, run through Cinch at the default settings:
172 KB → 14.9 KB— 91.4% smaller, in 123 ms.
You need Node.js 18.17 or newer.
git clone https://github.com/novolg/Cinch.git
cd Cinch
npm install
npm startYour browser opens at http://localhost:3777. On macOS you can also just double-click
launch.command in Finder — no terminal needed.
Then:
- Drag photos or a whole folder onto the window (or paste a path like
/Users/you/Picturesand press Enter). - Pick a preset, or set quality by hand.
- Press Optimize.
- Grab the results from the output folder, or download them as a ZIP.
Not sure what to pick? Start at the top.
| Preset | Format | Best for |
|---|---|---|
| AVIF Ultra | AVIF | The smallest possible files. Supported by every current browser. |
| WebP Balanced | WebP | Nearly as small, and readable by anything from the last decade. |
| MozJPEG Photo | JPEG | Photography where you want a plain .jpg at the end. |
| PNG Palette | PNG | Flat graphics, icons and screenshots with few colours. |
Everything is adjustable: quality, compression effort, maximum dimensions, whether to keep EXIF and GPS metadata, and a lossless mode for when the pixels must match exactly.
Compression is a judgement call, so Cinch never asks you to take it on faith. Preview any file to get a wipe slider between the original and the result — zoom in to 8×, pan around, and decide for yourself whether the setting holds up.
The same engine, without the browser:
# Convert a folder to AVIF
./cli.js ./my_photos -f avif -q 65 -o ./optimized
# WebP, resized down to Full HD
./cli.js ./my_photos -f webp -q 80 -w 1920
# Keep the original format, just squeeze it
./cli.js ./my_photos -f original -q 85After npm link the command is available anywhere as cinch.
| Flag | Meaning | Default |
|---|---|---|
-o, --output <dir> |
Where results are written | ./optimized_output |
-f, --format <type> |
avif, webp, jpeg, png, original |
webp |
-q, --quality <n> |
Quality, 1–100 | 80 |
-e, --effort <n> |
Compression effort, 0–9 — higher is smaller and slower | 6 |
-w, --max-width <px> |
Width limit, aspect ratio preserved | — |
-h, --max-height <px> |
Height limit, aspect ratio preserved | — |
--keep-exif |
Keep EXIF/ICC metadata instead of stripping it | off |
--lossless |
Lossless mode | off |
-r, --recursive |
Walk subdirectories | on |
Cinch is a thin layer over sharp and libvips, which do the actual encoding in native code — that is why a few hundred photos take seconds rather than minutes. Progress streams to the interface over a WebSocket, so a long batch stays honest about where it is, and can be paused or stopped mid-run.
server.js Express + WebSocket server
optimizer.js The encoding core (sharp / libvips)
cli.js Terminal interface
public/ Web interface — HTML, CSS, JS, no build step
icon.png Source logo; the web assets are generated from it
There is no bundler, no framework and no tracking. public/ is three files you can read in one sitting.
ISC — see LICENSE.