When comparing ImageOptim vs Spectacle, the Slant community recommends ImageOptim for most people. In the question“What are the best power user tools for macOS?” ImageOptim is ranked 8th while Spectacle is ranked 35th. The most important reason people chose ImageOptim is:
Great for compressing images for web usage or saving harddrive space.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Losslessly compresses PNG, GIF, and JPEG images
Great for compressing images for web usage or saving harddrive space.
Pro Fast & Simple
Pro Simple drag'n' drop interface
Simply drag images (or folders) into the window.
Pro Tries several different image optimizers before picking the best one
Pro Edits files in place
It does edit files in place, overwriting the original. This is exactly what I want, so I love it, but it's good to know beforehand.
Pro Can handle PNG, GIF, and JPEG images
Great for compressing images for web usage or saving harddrive space.
Pro Free and open source
Spectacle is licensed under MIT with source code available on GitHub.
Pro Simple hotkeys
Spectacle offers easy-to-remember preset hotkeys.
Pro Mouseless
All windows in Spectacle can be controlled with keyboard shortcuts, so no mouse is needed. This makes for a fast way to control windows.
Pro Great UX
Spectacle is easy to use and configure. It's plug and play.
Pro Low footprint
Spectacle only uses up 18-19 MB of RAM, which means there is not much overhead by using this app.
Pro Multi-monitor support
Pro 7+ years of use
Using it for 7 years
Cons
Con Compression algorithm not as good as counterparts
Con Cannot abort an optimization
Optimization can run for a long time. Sometimes it reaches 20% quickly and then spend a long time to attain 21.2%. But you cannot interrupt the process.
Con Does not work on SVG yet
Con Not maintained
The software is free, but no longer seems to be maintained.
Con Impossible to add new functions
While keyboard shortcuts can be changed for the available actions, there is no way to add custom actions which in turn limits the functionality of the app.
Con Limited window sizing capabilities
You can use 1/2 of the screen vertically and horizontally (divide into 4 parts). You can also use the screen in thirds too, but only the left and right third: you can't use the 1/3 in the center. There is no way to do a more granular distribution.
Con Breaks on macOS High Sierra / Chrome or Firefox
Doesn't support side by side windows.
Con Doesn't work with any Adobe products
There are some apps like Adobe Reader that do not work with Spectacle. Basically, any app with a heavily customized UI that breaks OS X accessibility will not work correctly under Spectacle.
