ImageOptim Changelog


  • Support for Apple Silicon CPUs
  • Updated OxiPNG
  • Updated MozJPEG
  • Updated pngquant
  • Updated SVGO
  • Updated guetzli
  • Requires macOS 10.15 (Catalina) or newer


  • Replaced old OptiPNG with OxiPNG — a fancy new parallel Rust rewrite
  • Experimental version of Sparkle updater testing new ed25519 signatures
  • Fixes for crashes especially frequent in macOS Mojave

This is the last version that supports macOS 10.14 (Mohave)


  • Support for SVG optimizations using Rust-based svgcleaner


  • Workaround Google Drive Stream filesystem


  • New icon by icons8
  • Added support for non-sRGB images in Guetzli
  • Updated translations


  • Added experimental Guetzli optimizer.
    • It's off by default (enable in Preferences), because it's very slow: 1 minute + 200MB RAM per megapixel. It is normal for a large photo to take 10 minutes and gigabytes of memory.
    • It's ineffective on JPEGs with quality 85 or lower. It's best to create JPEGs with 100% quality for running Guetzli on them.
    • Guetzli does not support color profiles, so only use sRGB.
    • Running Guetzli on the same image twice is not recommended, as it will decrease quality more than it reduces the file size. If you need smaller files, disable Guetzli, and enable Lossy mode instead.
  • Added new languages: Arabic, Finnish, Slovak, Ukrainian

This version requires at least macOS 10.9 (Mavericks), and full functionality is only available in macOS 10.10 (Yosemite) or later.


  • SVG optimizations via SVGO.

    • You must have Node.js 7 installed and enable SVGO in ImageOptim's Preferences first.
    • SVGO works best if you enable Lossy mode.
  • Big under-the-hood changes in handling of file inputs and outputs.

This version requires at least macOS 10.9 (Mavericks), and full functionality is only available in macOS 10.10 (Yosemite) or later.


  • Fixed Apple Mail extension code-signing issue.
  • Fixed stripping of color profiles when AdvPNG is enabled.
  • Updated Sparkle updater (auto-updates are much faster now).

This is the last version that supports macOS 10.8 (Mountain Lion)


  • Quick settings button in the main window.
  • Major update to gifsicle. It's faster and has higher quality.
  • Minor updates for Zopfli, pngquant2, jpegoptim.


  • Updated pngcrush
  • Fixed crash on startup


  • Much faster version of Zopfli (almost twice as fast)
  • Updated pngcrush, pngquant2, MozJPEG
  • Runs tools with lower priority (macOS 11+ only)
  • Updated Chinese localization (by pluwen)


  • Lossy GIF option. 50%-70% file size reduction!
  • Lossy conversion can be enabled permanently
  • Unified speed setting that controls all tools' compression/time trade-off
  • Romanian localization (thanks Oprea Nicolae)
  • Simplified Chinese localization (thanks asins)
  • Japanese localization updated (thanks KAMINO Aki)

This version requires at least macOS 10.8 (Mountain Lion), and full functionality is only available in macOS 10.10 (Yosemite) or later.


  • Switched from jpegrescan to MozJPEG
  • Add ability to temporarily enable lossy pngquant and MozJPEG re-encoding. The setting will switch itself off every time ImageOptim restarts
  • Added an App Extension that adds ImageOptimze option to images inside Apple Mail compose window (macOS 11+ only)
  • Fix for erroneous claim that files have already been optimized
  • Faster default settings for Macbook Air and older Macs
  • Fixed QuickLook animation on Yosemite
  • Gratuitous translucency in Yosemite
  • Updated translations and fixed help files

This version requires macOS 10.7 (Lion) or later, and full functionality is only available in macOS 10.10 (Yosemite).


  • Improved drag'n'drop of files outside ImageOptim window
  • Removed partial sandbox support that caused problems on some systems

This version requires macOS 10.7 (Lion) or later. If you have older macOS, please install the free system upgrade from Apple.


  • Option to Stop optimizations earlier (keeping progress made so far)
  • Removal of "Where from" macOS metadata
  • Lighter/faster default config on slow machines
  • Updated PngCrush, PNGOUT, ZopfliPNG
  • Autolayout used for the main window

ImageOptim 1.5.4

This is the last version that supports macOS 10.6 (Snow Leopard)

  • Added Revert to Original option (restores unoptimized file)
  • Added cache of already-optimized files. In some cases ImageOptim will be able to quickly skip files it knows it can't optimize any further

1.5.4a6 (experimental)

1.5.3 (unstable)

  • Fixed compatibility with older macOS
  • Fixed PNGOUT integration

1.5.2 (unstable)

  • Better compression on the first try due to improved management of temporary files and optimization parallelizm
  • Updated autoupdater
  • Improved Reveal in Finder
  • Fixed handling of relative paths when launched from CLI
  • Switched to newer APIs for path & file handling and simplified code for handling parallel queues


  • New: Copy as Data URL (copies small image files to clipboard as data:image/… URIs for easy inlining in CSS/HTML)
  • Less noisy output when run from command line
  • Updated translations for Russian, Czech, Danish, Greek, Italian, Japanese, Norwegian, Polish, Portugese, Turkish, Vietnamese and Chinese
  • Workaround for Code Signing problems (*shakes fist at Apple*)


  • Migrated to ARC memory management
  • Statusbar text with optimization result can be selected and copied
  • Lossy jpegoptim conversion (if enabled in Preferences) will be applied only if it gives >5% filesize gain
  • Updated Greek and Italian translations (thanks Giorgis Zacharakis and Oscar Fanelli)


  • New icon by Anna from icons8/VisualPharm! Crushed guy is now a magical press
  • Running from CLI directly is synchronous, hides the window and automatically quits when done:
    /Applications/ ~/Desktop/image.png
  • Purchased 1-year Developer ID from Apple to avoid blocking of independent software in Mountain Lion and Mavericks
  • Improved QuickLook integration
  • Fixed ⌥-click on Again button


  • Running optimizations again is much faster by skipping tools that are known not to improve compression when run second time
  • Improved backup of files on Samba network drives (10.8+ only)
  • Improved dragging and copy&paste of files in the list
  • Improved time-limiting of PNGOUT and Zopfli
  • Ability to disable dock bounce with defaults write net.pornel.imageoptim BounceDock -bool false


  • Fixed opening from Dock and command-line
  • ImageOptim won't try to optimize non-writeable files
  • Better cleanup of temporary files
  • Updated translations and added new:
    • Vietnamese (thanks to Biz Over and Phan Anh)
    • Turkish (thanks to Ali Riza Esin)
    • Czech (thanks to "fri")


Big thanks to James Stout for contributing several improvements in this release!

  • Zopfli compressor
  • Icons for “Retina” display
  • ImageOptimize service in Finder's context menu. You can disable it or add a keyboard shortcut in Finder → Services → Services Preferences…
  • Removal of Resource Forks and hidden attributes that inflated file size in Finder
  • Original images are “backed up” to Trash
  • ImageOptim no longer tries to be clever with preservation EXIF markers and always strips them when told to
  • Translations
    • Translations are now done via Transifex website. You can sign up and help!
    • Korean translation (thanks to Byung Hoon Cho)
    • Chinese translation (thanks to Jason C. Huang)
    • Lithuanian translation and updated Russian translation (thanks to Aleksandr Jadov)
  • Updated Pngcrush to 1.7.66
  • AppleScript command for checking how many optimizations are running (for integration with ImageOptim-CLI)
  • Overall optimization gain shown when optimizing same file multiple times
  • Tools are run in order that maximizes utilization of multicore CPUs


  • Added configurable columns (right-click table headers)
  • Status bar shows overall savings
  • Slowest settings are not used for very large files to avoid optimisation taking “forever”
  • Less aggressive optimization of GIF files to avoid bugs in Safari
  • British localisation
  • EXIF and color profiles are never stripped from large JPEG files (i.e. usually photos form digital cameras)


  • Included PNGOUT by default. Now ImageOptim includes all best optimisation tools out of the box!
  • Simplified preferences: options for stripping PNG chunks and JPEG EXIF data are in one place
  • Localization fixes by Gildas Lormeau
  • View Source option — because not only web apps have viewable source code :)


  • Removed troublesome optimisation from jpegrescan
  • Fixed jpegtran ran without jpegrescan
  • Updated Pngcrush to 1.7.22


  • Disabled jpegrescan due to compatibility problems
  • Updated Gifsicle to 1.64
  • Updated Pngcrush to 1.7.18
  • Fixed bug that could cause corruption of GIF files


  • Extended jpegtran optimisation with jpegrescan script by Loren Merritt
  • Norwegian Bokmål localization (thanks to Henrik Helmers)
  • Portuguese Brasil localization (thanks to Luiz Menezes)
  • Updated Gifsicle to 1.63
  • Fixed revealing of multiple files in Finder


  • Placeholder for drag'n'drop area
  • Running tools are immediately stopped when corresponding files are removed from the list
  • ⌥-clickOptimize again” to optimize only files that have previously been optimized successfully
  • ⌥-clickDelete” menu option to remove completed files
  • ⌘⌫ as well as and remove files from the list
  • File sizes are formatted according to system locale
  • Fixed Pngcrush integration freezing on some machines
  • Fixed Spanish localization


Major improvements in this release have been done by Reinhard Möller. Big thanks!

  • QuickLook integration
  • Added ability to copy, paste and drag files out of ImageOptim's window
  • Button to reveal files in Finder
  • UI improvements for macOS Lion
  • Fixed updating of file paths in preferences
  • Danish localization (thanks to Rasmus Kjær)
  • Spanish localization (thanks to Ben Pollard and Wayne Hartman)


  • Cosmetic UI fixes for macOS Lion
  • Dropped support for PowerPC
  • Dropped support for macOS 10.5 Leopard. Snow Leopard or Lion is required

ImageOptim 1.2.5

This is the last version that supports macOS 10.5 (Leopard) and PowerPC.

  • European Portugese localization (thanks to Sérgio Miranda)
  • Russian localization (thanks to Nicom)
  • Updated to Gifsicle 1.60
  • Updated to OptiPNG to 0.6.4
  • Updated to Pngcrush to 1.7.12


  • Italian localization (thanks to Fabio Sanna)
  • German localization (thanks to Alexander Mayer)
  • Updated versions of Gifsicle and OptiPNG
  • Fixed saving of AdvPNG-optimized images


  • Changed UI to match Leopard aesthetics (based on design by Martin Andersson from Auforia and Chris Messina)
  • Added Dutch localization by Mathias Bynens
  • Status column is sortable
  • Write errors are now properly reported
  • 64-bit and Snow Leopard compatibility improved

Current version of ImageOptim requires macOS 10.5.8 or newer. If you have older system you should either update it or use older version of ImageOptim.


  • Added French localization by Mathias Richter
  • Added modified version of optipng that clears dirty alpha transparency (RGB components of fully transparent pixels)
  • Added Gifsicle for optimisation of animated GIF files (use PNG instead of static GIFs!)
  • Added tools menu for quick disabling/enabling of tools used


  • Fixed progress indicator
  • Updated Polish translation


  • Leaner and more stable thanks to new Leopard APIs
  • Can handle order of magnitude more files at once
  • Avoids writing many files to disk at the same time
  • Checks actual file type rather than rely on filename extension
  • PNGOUT may be gracefully stopped if takes too much time to optimize
  • Temporary files are cleaned up on exit
  • Errors during optimisations don't slow down or lock up ImageOptim

ImageOptim 1.0.10

This is the last version that supports macOS Tiger.

ImageOptim 1.0.8

This is the last version that supports macOS Panther.