ImageOptim

ImageOptim optimizes images — so they take up less disk space and load faster — by finding best compression parameters and by removing unnecessary comments and color profiles. It handles PNG, JPEG and GIF animations.

ImageOptim seamlessly integrates best optimisation tools: PNGOUT, Zopfli, Pngcrush, AdvPNG, extended OptiPNG, JpegOptim, jpegrescan, jpegtran, and Gifsicle.

It's excellent for publishing images on the web (easily shrinks images “Saved for Web” in Photoshop) and also useful for making Mac and iPhone/iPad applications smaller (if you configure Xcode).

How to use it

Simply drag'n'drop images or folders into the window! They'll be optimized in-place.

You can also drop files on ImageOptim's Dock icon, or use Services menu in Finder, or launch it from a shell script.

More about PNG

My article “PNG that works” explains why ImageOptim removes gamma information and how to get even smaller PNG files with transparency that works in ancient versions of IE.

Open Source

ImageOptim is free, open-source software under terms of the GPL v2 or later. Your contributions are welcome! Please fork the source code on GitHub and improve it! Feel free to for assistance.

ImageOptim is sponsored by MaxCDN.

PNGOUT is bundled with permission of Ardfry Imaging, LLC and is not covered by the GPL.

Frequent answers

Images are brighter and desaturated in Preview.app!

Sorry, Apple broke gamma correction in Preview.app and QuickLook in OS X Mavericks. The bug has been confirmed by Apple as rdar://15303483. You see this problem, because ImageOptim losslessly converts some images to a more efficient (and perfectly valid) type of PNG that is affected.

Fortunately Safari, Photoshop and other applications/operating systems display these images properly, and the bug is going to be fixed in Mac OS X 10.9.2.

How does ImageOptim compare to TinyPNG and JPEGMini?

Tools like ImageAlpha/pngquant/TinyPNG and JPEGMini can make files much smaller using lossy compression which (slightly) lowers image quality. ImageOptim is lossless — it compresses image files without affecting quality.

For best results you should first compress images using a lossy tool and then apply ImageOptim for even better compression.

Will ImageOptim be in the App Store?

Unfortunately not. ImageOptim is given on terms that basically say “you can do whatever you want except taking away this freedom from others”. Apple does not allow such permissive terms. Apple requires all App Store users to accept legal restrictions in the iTunes EULA and puts DRM (copy protection) on all App Store apps.

You can get ImageOptim here, DRM-free. You can share it, modify it, use it in any country in the world, even sell it, as long as you don't forbid anybody else from doing the same.

You can donate to support the project.