Image Optimizer Plus for Windows

A lightweight, fast, lossless image optimizer for Windows, inspired by ImageOptim on the Mac.

Drop AVIF, GIF, ICO, JPEG, JPEG XL, PNG, SVG and WebP files (or whole folders) onto the window. Each file is optimized and replaced in place. There's nothing to configure: the defaults are safe, and a small Settings panel (gear button) is there if you want it.

You can also right-click images or folders in File Explorer and choose Optimize with Image Optimizer, or copy them in File Explorer and press Ctrl+V in the app. Selecting many files at once opens them all in one window.

Click the File, Size or Savings header to sort the list (click again to reverse it). The app follows the Windows light or dark app mode automatically, and uses your High Contrast colors when a contrast theme is on. It's in English, French, German, Italian, Japanese and Spanish, and follows the Windows display language.

Light	Dark

How it stays lossless and safe

1. The original is copied to a private temporary folder; the optimizers only ever see that copy.
2. The format's optimizer writes one or more candidates (for JPEG, both baseline and progressive).
3. Candidates that aren't strictly smaller than the original are thrown away.
4. The smallest candidate is decoded and compared pixel by pixel with the original (Windows imaging for PNG/JPEG, dwebp for WebP, avifdec for AVIF, djxl for JPEG XL, each PNG image inside an icon, and every frame of a GIF as browsers draw it, along with its timing and loop count). Any difference and it's discarded.
5. If the file changed on disk in the meantime, nothing is written.
6. Only then is the original swapped for the candidate in a single File.Replace step.

If anything fails along the way, the original file is left exactly as it was.

Format	Tool	What it does
AVIF	avifenc / avifdec from libavif	Lossless AVIFs are re-encoded losslessly at a higher effort (typically a few percent smaller). Lossy AVIFs are left untouched.
GIF	Gifsicle	-O3 lossless frame and LZW optimization. Removing metadata also drops other programs' data, such as XMP, unless the GIF has a color profile.
ICO	oxipng	Icons (.ico) and cursors (.cur): each PNG image inside is recompressed losslessly, keeping its color type and bit depth so Windows can still read it. BMP images are kept exactly.
JPEG	jpegtran from libjpeg-turbo	Optimized Huffman tables and progressive encoding, without touching the image data.
JPEG XL	cjxl / djxl from libjxl	Lossless JPEG XLs are re-encoded losslessly at a higher effort (typically a few percent smaller). Recompressed JPEGs are rebuilt and recompressed, and still turn back into the exact original JPEG. Lossy, animated and rotated JPEG XLs are left untouched.
PNG	oxipng	Lossless filter, bit depth, palette and deflate optimization. Animated PNGs are left untouched.
SVG	SVGO	SVGO's default preset, run in the built-in Jint engine (no Node.js needed). SVGs are text, so they aren't pixel-compared.
WebP	cwebp / from

By default metadata (EXIF, comments, camera info) is removed, but color profiles and JPEG orientation are always kept so images look exactly the same.

Settings

• Formats to optimize (AVIF, GIF, ICO, JPEG, JPEG XL, PNG, SVG, WebP)
• Remove metadata (on by default)
• Maximum compression: Zopfli for PNG, maximum effort for WebP, AVIF and JPEG XL, multipass SVGO (off by default; much slower)
• Use progressive JPEG when it's smaller (on by default)
• Keep each file's original "Date modified" (on by default)
• Ignore node_modules folders when adding a folder (on by default)
• Add "Optimize with Image Optimizer" to File Explorer's right-click menu (on by default)

Settings are stored in %AppData%\ImageOptimizer\settings.json.

Install

Get it from the Microsoft Store. The Store keeps it up to date, and uninstalling it from Windows Settings > Apps removes everything, including the File Explorer entry.

Requires Windows 10 (version 2004 or later) or Windows 11, x64.

If you installed an earlier version with ImageOptimizer-win-Setup.exe, uninstall that from Windows Settings > Apps too. It no longer receives updates.

If your antivirus blocks it

The app rewrites many image files in quick succession and runs bundled command-line tools, which some antivirus behavior checks mistake for ransomware. If yours blocks or closes it, report the false positive to the vendor (for Trend Micro, submit the file for analysis; on a work PC, ask your IT team).

Contributing

See CONTRIBUTING.md for how to build, test and release the app.

License

Image Optimizer is released under the MIT License. The bundled tools keep their own licenses; see THIRD-PARTY-NOTICES.md.