mytinypng

TinyPNG-quality batch image compression — as a CLI and a library. Re-encodes JPEG with mozjpeg, PNG with libimagequant + oxipng, and WebP/AVIF with libvips. Validated head-to-head against the real TinyPNG API (equal perceptual quality, equal-or-smaller files).

CLI

npx mytinypng <files | globs | dirs...> [options]

npx mytinypng image.png                 # -> image.min.png (never overwrites by default)
npx mytinypng "src/**/*.{png,jpg}" -w    # overwrite matches in place
npx mytinypng photos/ -r -o dist/        # mirror photos/ into dist/, compressed
npx mytinypng hero.png --to webp         # convert format
npx mytinypng banner.png --smart         # per-image adaptive quality (SSIM target)
npx mytinypng assets/ -r -w --cache      # idempotent — skip already-compressed files

Options

| Option | Description | | ------ | ----------- | | -o, --output <dir> | Write into <dir>, mirroring the input's relative path | | -w, --overwrite | Overwrite the originals in place | | --suffix <s> | Suffix for the default (non-overwrite) mode — default .min | | -q, --quality <1-100> | Fixed quality (default: tuned per format) | | --smart / --ssim <0-1> | Smallest output keeping perceptual SSIM ≥ target (default 0.99) | | --lossless | No quality loss | | --skip-oxipng | Skip the lossless PNG post-pass (faster) | | --cache / --cache-file <p> | Skip files already compressed by us (content-hash manifest) | | --force | Re-process even if cached | | -f, --to <fmt> | Convert to jpeg | png | webp | avif | | -r, --recursive | Recurse into directories | | --concurrency <n> | Parallel files (default: CPU cores) | | --dry-run / --json / --quiet | Preview / machine-readable / summary-only |

By default it writes a *.min.ext copy and never touches the original. Use -w to overwrite. It never produces a larger file — if compression can't beat the input, the original is kept.

Idempotency: with --overwrite, repeated runs would re-compress already-compressed files and slowly degrade them. --cache prevents this by recording the sha256 of every output and skipping matches on the next run.

Library

import { compress } from "mytinypng"; // re-exports mytinypng-core

const { data, compressedSize, ratio, skipped } = await compress(buffer, {
  format: "keep",      // "jpeg" | "png" | "webp" | "avif"
  quality: 80,         // omit for per-format defaults
  targetSsim: 0.99,    // optional smart mode
});

License

MIT