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Images by Edmund vs ImageOptim

ImageOptim has been in my Dock for years and it is very good at the job it does. Here is honestly where the two of them overlap, and the much larger part where they don’t.

ImageOptim makes a picture file smaller without changing the picture, and that is the whole job. It does it well, it is free, it is open source, and it runs on any Mac going back years, including the Intel ones. It also handles GIFs and SVGs, which mine doesn’t. What it doesn’t do is turn a HEIC into a JPEG, or make something 1200 pixels wide, or build you an app icon, and that is most of the reason I wrote mine. On the one thing they both do, they are level. I ran both over the same twelve wallpapers, 250 MB of PNG, and they finished within 0.2% of each other, with ImageOptim actually producing the smaller file on seven of the twelve. What you will feel is the time. Mine took 51 seconds. ImageOptim took ten minutes and twelve.

Side by side

The same job, two ways.

Images
ImageOptim
What it’s for
Converting, resizing and shrinking, nine jobs in one window
Shrinking. That’s the whole job, and it’s built around doing it properly.
Turning a HEIC into a JPEG
Yes, along with WebP, PNG, TIFF and the rest
No. It makes the file you give it smaller, it doesn’t change what kind of file it is.
Making something an exact width
Type 1200 and the height follows, across a whole folder
No
250 MB of PNG, twelve files
51 seconds
10 minutes 12 seconds
How small they came out
182.16 MB
182.53 MB, and smaller than mine on seven of the twelve files
Does the picture change
No. Every pixel identical.
No. Every pixel identical.
Your colour profile
Left alone
Stripped by default, along with the gamma. There’s a tick box for it in the preferences.
Making a Mac app icon
One picture in, a finished icon file out
No
GIFs and SVGs
Neither. Pictures only.
Both, and more JPEG tools than I ship
Price
Free, with nothing locked
Free, and open source, so you can go and read exactly what it does
What you need to run it
macOS 15 or later, and an Apple chip
Almost any Mac, including the Intel ones and some very old macOS versions
An honest steer

Neither one’s wrong. It depends on you.

Reach for ImageOptim when
  • You’re on an Intel Mac, or an older macOS. There is no build of mine for either and there won’t be, and this is the gap ImageOptim fills better than anything else.
  • You have the time and you want the smallest file there is. Given ten minutes it beat me on seven of the twelve, and if you’re shipping one hero image to a website that is worth having.
  • It’s a GIF or an SVG. I do neither.
  • You want to read the source, or you’d rather trust something that has been around and open for over a decade. Both fair.
Reach for Images by Edmund when
  • The job isn’t only “smaller”. Converting a folder of HEICs, getting everything to 1200 pixels wide, building an app icon: none of that is what ImageOptim is for.
  • You want it done now rather than in ten minutes. On these files that was the biggest difference between them by a distance.
  • The picture is colour-managed and you want it to stay that way. Mine keeps the profile, ImageOptim removes it unless you tell it not to.

Nine jobs, one window, on your own Mac.

Images by Edmund is free. Nothing locked, no adverts, and no account to make. The buttons below say where it has got to.

macOS 15 or later. Apple silicon Mac. Version 1.1.0, out 11 October 2026. What’s new.

Those sizes and times are one run, on one Mac, on my own twelve wallpapers, with ImageOptim 1.9.3 on its out-of-the-box settings against version 1.0.0 of mine. Your files will not be my files, and either app could change with any release, so take the numbers as a snapshot rather than a law. ImageOptim is also not slow by accident: the tools it runs are searching much harder than mine for the last few bytes, which is a perfectly reasonable thing to spend ten minutes on and is exactly why it won on seven of the twelve. This is about two apps shaped for different jobs, not about one being better. It has earned its place in my Dock and it isn’t going anywhere.